[moltensyntax]

Yes, this is possible, depending on the codec and container. I have done similar operations with h264+mp4.

It's good to be able to edit video without losing quality.

Are you sure you need sub-keyframe precision? In h264+aac+mp4, for example, if it's not keyframe aligned, the result is usually a stalled video frame for a split second, but since the audio continues smoothly, it's not that noticeable.

If you know the exact codec settings that were used to encode the video, you can create new pieces to be fit losslessly together. Otherwise, it is more difficult.

Contact me on twitter at @downpoured and I can describe more.