Recuva and unreadable file

On my side I am retrying to recover 350 videos is several formats (avi, ogg, mpeg, flv, ..) from an internal Harddisk.

The nice thing is to see that 66% of the files appear in 'Excellent shape', but

- > but.. none is actually readable at all at test.

- > The format is not even recognized by any of the 5 video-repair-softwares I tested yet (seems not identifiable at all)

- > indeed, it only expresses that clusters appear not overwritten

but what does the green light and that comment about recoverable and not recoverable finally mean (or help to understand) if eventually anything can be recovered ?

I saw that other users had exactly same experience and I wonder what it is about

Thanks and happy for any comment or explanation here.