A "comp" often stands for "compilation." This could be several clips of webcam footage (vlogs, video diary entries, or reaction videos) stitched together.
If the file opens but you only hear sound or see a black screen, you may be missing a specific codec . Try installing the K-Lite Codec Pack or using VLC.
Recorded Zoom, Skype, or Discord calls that have been exported as a Matroska (.mkv) file. 🛠️ How to Check the Content Safely
If you or someone you know uses software like OBS Studio , this might be a collection of "facecam" highlights from a gaming session.
Open it with . It is the most reliable tool for .mkv files and can handle most video codecs. Check for Malware: