AndrewMag.net

YouTube can accept almost any video format for upload, but for most users we have found the following settings give the best results.
Video Format: H.264, MPEG-2 or MPEG-4 preferred
Aspect Ratio: Native aspect ratio without letterboxing (examples: 4:3, 16:9)
Resolution: 640×360 (16:9) or 480×360 (4:3) recommended
Audio Format: MP3 or AAC preferred
Frames per second: 30
Maximum length: 10 minutes (we recommend 2-3 minutes)
Maximum file size: 1 GB

(from Youtube's handbook)

You might want to convert DTS to AC3.It is not that hard to convert.Here is what i use to convert DTS to AC3 :

1.tsMuxerR (Demux the DTS track from the mkv file)

2.Tranzcode (It will convert the DTS track into 6 mono wav files)

3.WAV to AC3 Encoder 4.1 (It converts those 6 mono wav files above into an AC3 file)

4.MkvToolNix (Remux the AC3.You will be given an option whether to keep the original DTS track or not.If you don’t want it.Simply uncheck it from the list)

P.S:Tranzcode doesn’t like long file name.If you find yourself cannot run it.Your file name is probably too long

http://wdtvhd.com/index.php?showtopic=6928

640×480 mp4 best
448 video 2-pass VBR
+64 audio 44,100 stereo
=512

640×360  16  320×180 9  =16×9
over