I am sure some of the very early film footage captured
and edited on various
proprietary computer hardware will be hard to work with (early 68K AVIDs for
one that needed specific hardware for compression/decompression). Video
compression has changed quite a bit over the last 20+ years I would think.
Video and audio formats tend to be well documented, but often
difficult to get ($$$$$!). Many of the big film and video labs have
this information, as they actually need to use it from time to time
for media conversions. Realize that Hollywood has lots of money.
I actually can not think of a single audio or video format that has
been truly lost.
--
Will