Thanks for the embedding - I was just coming back to learn how to do it.
The flickering is sunlight and waves ten feet above. I don't know what to do about that except maybe bring down an umbrella and use lights LOL I have lights but did not use them.
I was zoomed in, but not quite far enough as you can see from the vignetting. I'm in maximum learning mode as it was the very first time I've ever tried to use a diopter.
One thing that kept me from zooming more was the loss of focus if I zoomed in more. If I moved back a bit I might have done better - I'll try that next time. There's a pretty narrow depth of field with the +10, so distances are kind of touchy; a little more zoom, or a little more distance and things get out of focus in a hurry! I also have a +5 which hasn't been tried yet. Not to mention the surge...
Nudibranchs abound at "the bridge." If you look for Caribbean Sea Slugs at Amazon, you'll see there are quite a few there. One co-author is my source for the ID above. Not sure but I am under the impression there are more than 100 species of slugs and nudis at the bridge. More than 300 species of undersea critters have been documented there including seahorses, frogfish (we saw seven there last week) blennies of all descriptions and and and
I predict you'll like it!