I don't believe YT transcodes during upload, since last I checked they are doing 2-pass encoding (its been awhile though). However they do examine the buffer d

I don't believe YT transcodes during upload, since last I checked they are doing 2-pass encoding (its been awhile though). However they do examine the buffer during an upload. Try uploading an MOV with bad edit points, they will warn you about A/V sync issues before the upload is complete. I assume they also abort uploads for invalid files.