There are so many it's hard to list them all, but here are a few to start with.
One of my favorite presenters is dighsx. Not a whole lot of pipe reviews specifically, but he just makes great video's while talking about pipes or cigars, but also asking real questions that just make you think. He's a really cool guy.
http://www.youtube.com/user/dighsx
Another favorite is the Dagners. The father and son duo of Jay and Jayson are great. Jayson also has his own channel as well.
http://www.youtube.com/user/SmokingDagners
http://www.youtube.com/user/dagnerperformance
Another cool guy is Astroman2112. He does a good job presenting pipes, sharing his thoughts on them as well as reviewing tobacco.
http://www.youtube.com/user/astroman2112
If you're a fan of xecutech then you'll probably like TobaccoFrank. He does a good job with his video's as well.
http://www.youtube.com/user/tobaccofrank/videos
StevenW140 as previously mentioned is really cool too. I've actually hung out with him in person several times as we live within about 30 minutes of one another.
SmokingRingsPipeDreams, also previously mentioned, is another great presenter. Kel does a great job with his video's. He's actually the reason I decided to take up pipe smoking in the first place. After always wanting to try smoking a pipe, his video's finally made me take the plunge.
If you want to check out my channel you can find it here.
http://www.youtube.com/user/metalheadYcigarguy
I'm not great, but I enjoy making video's as it's better than just sitting by myself half the time with no one to share a pipe or cigar with so it helps in that regard.