I have a solution!!! I cant beleve how easy it was everyone on the forum with this problem will love how simple it its!
Just find someone with Mountain Lion and copy that version of "Movie.qlgenerator"
System/library/Quicklook/Movie.qlgenerator
....paste into your Mavericks System/library/Quicklook/ folder.
Reset your machine, all your old legacy thumbnails of quicktime return!!!! Still no ability to play but solves half the frustration. Hopefully Apple wil make a update if enough of us complain.
Why Apple developers thought it was a good idea to give us all a headache on dropping legacy QT previews I will never know!
(Just be on the safe side make sure you copy and paste the Mavericks "Movie.qlgenerator" to your desk top incase people have a diferent version and it brakes something)