On Stack Overflow, code review questions are off-topic and are migrated to CodeReview.SE.
On Programmers.SE, questions asking to review a particular architecture or design are mostly on-topic (unless too specific).
On Photo.SE, I believe questions asking for review and critique are off-topic. I've never seen there any question posting a photo and simply asking for critique. There are other websites, especially 1x, where the person can receive [mostly] constructive critique.
What about Video.SE? Can I post a link to a video I've done and ask for constructive critique?
If not, what can I do to improve my skills, given that books won't necessarily tell me that I'm doing something wrong?