The newly found tapes recorded them performing more than 200 cover versions of work by the artists who had influenced them: Chuck Berry, Elvis Presley and Buddy Holly.
Apparently this is audio and video of the Beatles last recording session together. This is the one where they did their famous rooftop performance. The Let It Be Wikipedia article tells a bit more about that session. I’m sure this means a splurge of new Beatles tunes a few months from now.