The magic bytes (those at the beginning of the files) are 0x0f 0xf5 0x12 0xed which correspond to the "XCOMPRESS_FILE_IDENTIFIER_LZXTDECODE" format.
Basically the Xbox (all of them?) use two native compressed formats that are supported by the xbdecompress tool of xsdk.
Luckily there is a script that works with all these compressed formats:http://aluigi.org/bms/xcompress_file.bms
Once the file is decompressed you can access its content.
For example f99233e5b181fbc70bc37902ea64cff4 is a "VIDE" file, it looks just like a simple container for a BIK video (radgametools) so you can play it after deleting the first 24 bytes.