how long should video intro's be?

i would recommend about 4 seconds. Dont do a long intro unless it is fun to watch. Mine is just 4 seconds
8 seconds absolute max. Aim for 4 or 5 seconds. A long intro will stop people watching the video before it even starts.
I hate when people have long intros. 10 seconds max. I'm uncomfortable using an intro over 7 seconds myself.

As for outros, it really depends on the point of the outro, but I never find long outros annoying. They just give me more time to avoid the post-roll ads that lots of people seem to use these days.
:help: I am currenly making an intro for my new aliens gameplay series and I dont know how long should video intro's be?, can any one help me in this time of crysis :bounce:
i actually have 2 intros the machinima and my intro which lasts about 25 seconds for both but people enjoy it because of the background music :)
The shorter the better!
People clicked on your videosince they want to watch the content - not watch a boring 10-20 sec intro before they get what they wanted!