Here are some thoughts on an approach to your problems.
Here and Now. I think the sad fact of life is that when it comes to permanent archiving of anything over tens of years, it is simply not possible to copy it somehow to some support and then put it in a vault and forget about it. Tape and current storage technologies do not permit this level of security and I doubt if anything is coming in the next 20 years that will adequately address the problem (I hope that I am proved wrong). That's the bottom line. Talk about archive formats addresses important issues of data formats and supports: the general objective is to find a stable support which will last a long time and not to unacceptably compromise your quality by choosing a good method of recording the data onto that support.
This has to be the starting point, and archive preservation becomes as a consequence not only a technical matter but 50% also a management strategy, requiring regular and planned intervention, and anticipating rather than reacting to problems. It must take into account the need to migrate to new supports regularly, say every 10 years (longer with luck). It must use the most appropriate technology available now within your budget, and meeting your quality criteria. Don't wait for tomorrow. It must take into account the possibility of physical damage by fire, flooding or machine malfunction. It must also take into account that no single support can be guaranteed to last indefinitely - accelerated testing and manufacturers claims apart -, there is the additional danger of unforeseen modes of deterioration. There must be planned continuous quality control, on the preservation copies, with appropriate measurements of error rates or drop outs, so that a good percentage of the copies are checked every (say) 3 years. (There are books and methods in management and systems courses to plan this - it need not be heavy to be effective). Chose good storage systems. Keep a thorough database. Use separate work copies for routine access and avoid touching the preservation copies. There must be a regular planned assessment of the technologies being actually used and assessments of the advantages of any new technologies. If you have got material now, start now, using the best techniques available now. Don't plan on the speculation and hopes of others becoming reality.
Part of any preservation strategy then must be to hold two preservation copies, each on a different support, and that these be stored in separate locations.
Migration in digital is more transparent and technically easier: the problem with digital is being sure that the players are around when you want to migrate. This you address in your management planning.
Make clear as well the distinction between how you encode the audio and video, and how you then store it. In the IT world, you can change storage medium without changing the encoding - transparently.
Since you are originating video at 'domestic' quality, I would suggest that digitising your video using a good quality capture card in a PC and bit rates of a few Mbps - or buy the systems for transferring the DV stream from the camera tape direct to disc: this will preserve essentially the original quality of the video from a domestic DV camera you seem to be using. Perhaps a higher bit rate is appropriate for SP and other 'professional' recordings. The hardware is not too expensive. If you use one of the recognized subsets of the MPEG2 formats, (see ebu/smpte report on harmonization) as used in DVB and ATSC, then you should be reasonably future proofed for a while. This has got your video as far as a hard disc. Now look to how you are going to store it. Burning a DVD either as a DVD-Video or DVD-R is one option. I have my doubts about the longetivity of recordable CDRs, and the JITS2000 archive conference in Paris earlier this year went into a lot of detail about the problems with it (I have copies if you want). I imagine DVD will be much the same. Nevertheless it is a good option for one of the preservation copies. A second copy kept as computer files on (say) a local server with RAID discs and/or on storage space rented over the internet seems a good option and reasonably secure. The details depend on the local market in your part of the world. Having got this far, additional storage on audio or video tape is a step backwards, and I do not recommend it. Another problem with this is that you have to go to the professional video formats which are expensive machines for the quality of video you are now originating. The IT solutions suggested are correct for domestic digital cameras.
A similar approach can be used for audio: a CDR (as now) and server and/or internet storage is also interesting.
An advantage of the IT approach is that your material is already there on a server if you are planning putting it on the web.
IBM and Sony (amongst others I am sure) also have services for storing and accessing audio and video via a private or public web type front end. You are then paying for a service rather than having to manage the storage technology yourself. I cannot say if this is more economic.
Concerning the debate about analogue versus digital: I accept that an analogue machine for audio or video is probably more easily re-constructed and mad-to-work than a digital machine. However - if you get your management strategy in place, you are addressing the problem of obsolescence by regularly assessing the state of the technological market and state of your recordings. It is a proactive strategy.
I hope that this is of some help.
Best Wishes Tony Gardner European Commission AV Service (Europe) All opinions are my own.