On trills:
Here’s John McLaughlin.
Notice how the trilling action at 0:25 is generated by planting the index finger and rocking the wrist back and forth. This allows the trill to be executed with a faster movement pattern that naturally synchronises to his picking technique.
I wrote more about John’s rocking mechanics here (and in the comments that follow):
And here’s Marshall, trilling by alternating different fingers to avoid the finger reuse problem.
That entire video of Marshall is full of ridiculous stuff.