What model of camcorder did this video come from and how did you get it into your computer?
When you set up your Premiere Elements project, which settings did you select?
What is your computer's operating system, processor speed and RAM load?
Have you ensured you have the latest version of Quicktime from Apple.com, per the program's requirements?
Welcome to the forum.
Along with Steve's important questions, how did you Import your AV file into PrE's Project, and do you now have it on the Timeline?
Any error/warning messages?
In the Project Panel, what is showing for that Clip? Is it just an icon, and if so, please describe it?
Good luck, and please let us know more,
did you get your problem sorted?
This is a 2011 thread that you are posting now in 2014.
Best start your own new thread with the details of your specific situation.
Problems with the same symptoms can (often do) have different causes.
For starters, what version of Premiere Elements do you have and on what computer operating system is it running?
The answers will be in the details, so lot of details please.
Looking forward to your follow up in your own new thread.