There's a big back and forth toggle war on whether or not behind-scene photos should be used on your actor website. When I first started hosting actor websites, to me it seemed as unnecessary trend. If you keep your website simple and post your headshots only, it will make it look a little more professional. Mind you, that was then.
After years of tracking and analyzing statistical data I can give you my expert opinion without any hesitation. Do it! Behind the scene photos will engage your viewers and will keep them on your website longer.
You know what they say about statistics, right? If you're walking a dog, statistically everybody has 3 legs. But with enough analysis it's easy to follow trends and see what works and what doesn't. Having a single headshot on your website has a negative effect. Majority of your visitors open your page and almost immediately close it, without clicking on anything else. Having multiple headshots will leads people to spending more time on the page and has higher probability of them clicking to go to another page. Having headshots and "other" photos, (call them what you will), increases the likelihood of people clicking through to other pages by whopping 40%. Hey, I'm no gambling man, but I'll play those odds.
First of all, let me point out that if you're a part of a big production and you take your phone out and start taking selfies left and right, you may not have employment for long. However, if you have photos hanging out with some costars we might recognize, or photos wearing costumes or signature makeup, pop that on your website for a higher retention rate.
However, make sure your separate those from your standard headshots. If it IS a casting director looking at your website, you don't want them be overwhelmed by the number of photos and trying to figure out which photos to look at, so make sure you create proper galleries within your website.