Social media is clogged with live footage from the protests. Can you find a single video of an ambulance being stopped by protests?
The irony of your comment is that the likelihood of an ambulance being close to a protest is linked to the extreme violence that the police is using to attack and repress protests against police violence.
Why would anyone make a video of stopped traffic?
Anyways, if you're trapped in traffic and not moving, there's not much else for you to do besides get out your phone and take some video.
Because people like you are hell bent on smearing the protests, resorting even to come up with made-up accusations like ambulances stuck in traffic, and any evidence would provide some support to those claims.
But apparently even that is hard to come by. So here we are, stuck with fabrications and imaginary "what if" scenarios.