I'm looking for a video or tutorial on how to knit a flat hat with straight needles?
There are (supposedly) 153 pages of them at Ravelry (free to join): http://www.ravelry.com/patterns/search#craft=knitting&query=hat&pa=worked-flat&view=captioned_thumbs&sort=best
Just find a pattern and it will have everything in it that you need.
Here's a bit of explanation and a pattern for knitting a hat on straight needles. Most of the tutorials are for knitting in the round.http://sghupp.hubpages.com/hub/How-To-Knit-An-Easy-Hat-On-Straight-Needles
Here's a few.
This one is knit flat, but uses short row shaping at the crown. http://tiajudy.com/gartercaps.htm
I might make one just to see how the short row shaping works, it might be useful in other projects. Thanks for the link!