All under the assumption that the venue was as-is real-life location in the scene, I am trying to pursue this through the Reggae and flag leads - no result, but posting as food for thought again.
Incidentally I just recently learned from some Jamaicans that their countymen like to settle in Broward (as opposed to Miami-Dade). Indeed, South Florida is the second highest concentration of Jamaicans in the US after New York, but there are no significan communities in central Miami-Dade, though plenty further north (source):
Yes, Broward is far from the other locations, but I just like to explore and who knows where it could lead. Upon googling relevant places though, I didn't find much, neither in the 80s nor now, except this Caribbean tiki bar with a music stage in Hollywood, which also had trellis fencing similar to the one in the scene, but this place was just recently built:
All that is not to say that a Reggae band has to play where Jamaicans live... but a higher chance maybe. Speaking of the band, finding out its name appears to be impossible (knowing the name could lead to their possible regular venues) - all we know is that they were playing Bob Marley's Jamming.
The second research track is the flag, and here it is again, now with enhanced color:
I'm no vexillologist, but I'm fairly sure it's not a country flag. If you assume this is a horizontal flag that is hung sideways, as is often done with flags, it becomes this:
Lots of country flags have some kind of inner rectangle top left (in fact like the star-spangled banner) and having something that looks like a coat of arms in there would be also very appropriate, but no country flags really have thin vertical stripes, that's unusual.
Could it be a maritime flag?
Wouldn't be inappropriate, Miami is on the water after all. And plenty of vertical stripes there, but again no match. @Tom could you possibly pull out an enhanced image version from your MV copy to try and discern if that's some heraldic symbol?
Let's continue brainstorming!