برنامج avidemux لقطع ودمج الفيديوهات

Avidemux is a graphical tool to edit videos. It can open AVI, openDML, MPEG, Nuppelvideo, and BMPs. Most common codecs are supported (M-JPEG, MPEG, DivX, Xvid, huffyuv, WMA, etc.) thanks to libavcodec and libmpeg2. Video can be edited, cut, appended, filtered (resize/crop/denoise), and re-encoded to either AVI (MPEG4/MJPEG) or MPEG 1/2. The Spidermonkey Javascript engine is used to give powerful scripting capabilities.
To split a file or a section of a file do the following:

1. Open and select the file you want to split (File / Open).
2. Then, with the bar below, select the point where we want to start our video and clicking on the letter A using icon  ( or press [ ) and mark point B  ( or press ] ) where you want to end (cut) your video.
3. Finally from the menu select File / Save / Save Video

how to join files in Avidemux?

 In Avidemux select video=copy, audio=copy, format=mp4.

Click on File>Open and select 1.mp4 then click on File>Append and select 2.mp4 then 3.mp4 and the rest of your files.

Click on File>Save>Save Video to save your output file and give it a name and extension of mp4 such as [final_file.mp4]