I have 1 subs file for a film that has been split into CD1 and CD2 .avi files. How can I sync the subs for the second file on YouTube?
You can use Subtitle Edit - see
www.nikse.dk
Load the subtitle file and split it into two pieces (Tools - Split subtitle...)
You have now two subtitle files.
Assuming that the subtitle for the first part is synchronised well, the subtitle for the second part just needs a linear shift (Synchronisation - Adjust all times).