I really have no explanation for you on the errant shot. I've had a few over the years that were 100fps off and I had no explanation for them either. Sometimes I think we are just victims of a culmination of errors in material. It doesn't take much to throw off a load by that much so a small sample of the powder might be off enough to cause the issue. As much as we'd like to think the components are all the same, they really aren't. A bullet that weighs a grain or two less, a primer that has a bit more power, powder that has a disproportionate number of half grains, a case that has a different neck tension. Add them all up in one round and maybe....

Sounds like you have a decent setup. I'd probably still be using a Chrony if not for the time of day I shoot, ie, I start a bit before sunrise and optical screens aren't reliable in a light like that.

I mounted a good camera on the bench and it works well. If mirage isn't bad I can even see bullet holes at 500yd. The video gives some great information, especially when the shots are erratic. Watching the 'bullet trail' as the bullet descends into a target at long is fun by itself. And being able to go back and see shot placement is a bonus.