Here is the evidence, you be the judge.
To access hi-def clips:
The YouTube "Smoking Gun" Video
I have been searching for evidence to confirm my suspicions and I think I have enough now to confirm that the NHL did, in fact, fail to award the Sabres a goal on a Toni Lydman shot in the first period of Game 2 of the conference finals.
In the following pictures taken from a high definition DVR and video from YouTube, you will see the puck enter the net and come out after disappearing into the net.
In the video you will see the play in regular, slo-mo, and close-up slo-mo replays.
While I can understand how this goal was missed I find it unacceptable in a major professional league that things like this continue to happen. I also firmly believe that the NHL was fully aware of their mistake. I say this because in the 3rd period, two separate times, the video goal judge had Ray Emery remove the water bottles on top of the net. Oddly enough the placement of these water bottles coincides directly with where the puck appears to have struck the back crossbar on the net.
Memo to the NHL:
If you want to be a big-time sport the officiating must get better! Hiding this from the public does not help your cause.
Shame on you.