Watched the video. Can't tell you specificallly what is wrong yet, but llet's drill down.
First, no disrespect to anyone, but generic suggestions about replacing all the boards are a poor solution. It may be a soution for some, but not everyone. Why?
1) In MOST cases, you can get your boards repaired for far less than the $$ you'll spend on a new boardset, or what you think might be the issue. I just fixed a battery damaged System 11 MPU for one of the members here whose customer was about to pop big $$ on a new display - which was not going to fix the problem. Also, not everyone can afford to spend $$ on new boards.
2) Original boards were built for COMMERCIAL USE and designed to be "tasked" in severe environments - i.e., arcades, bowling alleys, etc. They are even less stressed under home use, so carefully rebuilt and upgraded boards still outweigh the cost of new.
3) One of the things that MPU sellers tout as "a wonderful feature" is it's ability to be used in many different games. For the casual user, they are going to stick it in one game and keep it there - so it's a moot selling feature.
OFF soapbox, on to the issue at hand.
In Harlem Globetrotters, solenoid 8 is for the right popbumper - check your right popbumper coil, be sure the wrapper is not burned or discolored. Solenoid 11 is for the coin door lockout - check the small solenoid inside the coin door to see if it is also burned up. Like the popbumper should have "popped" in self test, the coin door solenoid should have "clicked".
Sound board oddities - well, sound board did not sound right on game startup- it played some very high notes in with the others. Also note that the sound board IS on the test routine, after the solenoids - so the sound board going off may have just been the test routine, albeit pitched highly.
The sound board may need some attention. try fiddling with the two pots - one is for volume, one is for sustain. The sustain one is tricky - if it gets turned up too much, the notes will all blare and never be separated. ALSO: An old sound board like this should be recapped, replacing all the old electrolytic caps.
Check the solenoids first. The popbumper is critical, the coin lockout is not. You said the driver board was rebuilt - are you certain it's 100%? IF you require help with the sound board I am always available for board maintenance and repairs.
Good luck!
Chris