If you have a file ending in .001 (and possibly .002, etc.), here is the correct technical procedure to attempt reconstruction — but only if you are certain the content is legal in your country.
# Using 7-Zip:
7z a -v100m myvideo.avi.001 myvideo.avi
This creates 100MB chunks.
After joining, you should get a single .avi video file. If the file is password-protected or missing parts, it will fail. MAXD 08 Aya Fujii The Dog Game 2 NEW.avi.001 Chiara Buono