Browse to the start of the commercials, highlighting the first frame you want removed.If you kept a recorded of the times the commercials appeared then check this, or check the original MythTV recording, otherwise they may be a little tricky to find. Now browse to the first set of commercials.Hit the 'Selection: End' button (the blue one with a B after it) and click Edit > Cut in the menu.

Make sure that the frame highlighted is the first one you want at the start of your recording. Use the 'Previous Frame' and 'Next Frame' buttons (just after play / stop) to navigate to the exact starting frame of the show.

Drag the video slider (just underneath the video screen) to the start of the movie.Click the 'Open' button and chose the required file to open.Start Avidemux 2 through a shortcut or by typing 'avidemux2' at a command prompt.This section is mainly produced to support the Nuvexport guide, though will give you simple instructions on how to cut out sections and save a file in the same format. It should take just 1-5 minutes to save a few Gb nuv. This tells avidemux to just pass the DVD through without altering it (apart from the cut points obviously). 4.1 Trimming the top+bottom black bars and saving a film as a 16:9 DVD.

Avidemux cut