Actually, when I just want to test something silly, I often just go to ~, make a file test.c or something, write the short test program, and run `gcc -o test test.c`. It's not that rare to have videos in your home directory, and if I had one named a.out, and forgot the -o option, it'd get overwritten.

Not saying it's remotely likely, just saying that having video files in a program's source tree isn't the only way it could happen :)