I think the differant variations of the bridge are great exercises for the hamstrings and lower back. I'm not talking about doing the wrestler bridge with nose touching the matt and holding forever. That's eventually going to cause most people more pain down the road, atleast that's the way I felt.

No expert but from the way it feels for me feeling the glutes work makes my back feel so much better. A couple of things I like to share that Matt doesn't talk about in this video on how to help in activating the glutes. On thing You can do is put Your sneakers in between Your knees and squeeze as You do the bridge. I learned this from Pavel's book S&S.

Another thing I like is putting a resistance band or cable around my knees. This keeps constant pressure in and I can really feel it work there.