Hi Peter Piper
Just passed by to welcome you to the forum, I,m no video Wiz myself
The problem of sizes is a complex one as there are many different video formats available some allow compression and others dont but to allow you to do certain operations with many formats they are usually uncompressed and expanded to there pre compressed state before doing any new operations, this of course means something that may well fit on a CD is now 3GB in size on your hard disk, annoying, but temporary.
There are many programs available to split and compress files over the 4.7 GB dvd size length, I,m sure after testing many solutions you know them better than myself, but I,ll leave any particular brand suggestions for our resident video Guru
I,m sure its only commercial releases with extra scenes and multiple languages that normally go above the dvd limit anyway, most dvds above that will easily fit on the dvd dual layer disk as you suggest, for backup purposes of course.
For many of the video types I have seen I prefer the xvid versions as the compression to quality ratio is rather good.
I,ll leave a more detailed reply to your post to those who are a bit more knowledgable than myself, but nice to have you here : )