I do not think you will get anywhere with this one. Firstly only files with a valid video extension will be shown in the video partition and only ones with .mp3 extensions in the audio partition.
There is no way afaik to build a repeat play into the box by adding something to a file. It would have to be built into the box software.
Never tried this but if the box plays the next file automatically you could add multiple copies of the same content with slightly different filenames (add a numeric subscript eg xxxxO1.ts. xxxx02.ts etc).