Add first and last frame view and various trim/cut options

[scottmc]

Maybe on the advanced tab? Add extra abilities such as trim/cut, cropping, and/or other features.

Add a trim/cut feature to allow cutting before the first selected frame, after second selected frame, or to cut out the part between the two. This is probably the most common thing I use ffmpeg for, this is useful for taking that short video you took with your phone but the clip had a bad start or ending to it. Or there are parts in the middle you don't care to keep, etc. Perhaps show the frame at the two points and a control to let the user move forward or back to find the spot they want to cut at.