YouTube actually seems to work a bit better for posting videos. You can set them up so only people with a link can see it, and then post the link here.
I think you're putting the cart before the horse with respect to working on form. There are a lot of things you can "get away with" with a lighter weight, that you can't do when the weight is actually heavy (in this case, I mean, 85% of your 1RM or heavier). You can have picture perfect form with just the bar, but that form may not actually work for you once you're lifting heavier. No matter how much time and practice you put in with the lighter weight.
On the other hand, if you work toward having "pretty good" form with a heavier weight -- making adjustments and trying things that keep you tighter and more solid, and able to move more -- you can then practice and refine that form with a lighter weight. I think experience with heavy weight is required to even learn what "good form" is, for you. What works for one person doesn't always work for someone else.
That's not to say that there's no value to mobility and flexibility work, or that form doesn't matter. Just that putting too much work into form work up front may not be the best use of your time.
FWIW, just my opinion/observation/experience, not prescriptive by any means.