Engineers are one of the more under appreciated classes in Team Fortress 2
. Much like a lineman in football they are critical to the game but rarely get the attention of the so called skill positions. Here's a video from the the folks over at Machinma
.com have that shows you most of the tips of the trade on how to be an effective engineer. I think the only thing they left out was how to use the dispensers and teleporters as cheap spy detectors but that's probably in store for a future video.
Thanks to Kotaku
for the link.