[theora] How to merge and cut theora videos, and how to synchronize sound?

[Lucas Malor]

Hello. Excuse me in advance for these dumb questions.

I used ffmpeg2theora to convert much videos. Now I would cut and/or merge them. How can I do it?

Furthermore, in many cases the sound was desynchronized - I converted TS mpegs. I tried to add the sync flag with bad effects. How can I manually delay / anticipate sound track?