but what is that water coming from the left side LEFT of the wall at the beginning of the video?
It is slightly upstream on the main break....you can really see at 28sec before the zoom to the bottom
Good catch. That is a drain pipe that normally would go to the sidewall outlet. The connecting pipe to the left sidewall outlet was broken away from this point from either the backfill erosion damage and/or from the sidewall & slab shift.
The video only gives a good view of the right sidewall drains. So this "catch" on this drain demonstrates there is water penetration about 100 to 200 ft further up the spillway -OR- there is a subsurface flow that is coming from an unexpected "piping" path within the lower rock. Something to keep an eye on.
I see that, now that you point it out.
Must be a broken drain.