Youtube plugin downloads rubbish

Hi (ahoj),
suddenly youtube pluggin stopped working for me. It downloads rubbish. Whereas healthy flv file starts with letters FLV (46 4C 56 hex), my downloaded flv files start with 1A 45 DF A3 01 hex.
Another strange thing - whereas good files downloaded via Youtube Downloader HD has cca 30 MB, corrupted files has cca 40MB !

My FRD version is 0.85u1
Version of youtube plugin is 0.8.4.

Example of bad address is here

[www.youtube.com]

If you should need, I'll post corrupt file to Megaupload.

Thanks, JN, Czech rep.

Same problem..