Retrieve files protected by NQVault due to forgotten password
Apparently, NQVault does not really encrypt the files, but simply does a byte-by-byte xor operation with a key that is generated from the password. Oh, and it does that only for the first 128 bytes. Since a byte can only take 256 different values, you can simply brute-force the key you need to "decrypt" your file.
The author of the linked post has even published the code for a brute force attack. All you need to do is to compile the c code, edit the bash script to recognize whatever mime type your videos are and then run the script.