I'm no expert video editor, but there does not seem to be anything out of place in that video. Everything is plausible from wind, hair, shadows, water, angle/plane, the bicyclists, etc.
I think people just have too much time on their hands lately and have nothing better to do than look for conspiracy theories in videos. On the other side of the fence, I'm noticing some folks not buying into the fear the media is perpetuating (or just getting tired of this) and choose to continue to live their lives. I'm seeing a lot more people being active in public places like beaches, hiking trails, parks, etc. because what else you gonna do? Everything's closed. And those folks that want to be active would not be into wearing masks, etc. So a populated beach/walking path does not surprise me.
With that said, if you or a loved one are at risk or has contracted it, do your part to stay safe like with any illness, and I pray you heal and recover without issue.