We need a LOT more info to even begin helping.
Mac or PC?
What is the SOURCE video codec/specs?
Some video files will be difficult to play back in Premiere if your system hardware is not fast enough. Your rendering may be defaulted to UNCOMPRESSED, which can create a file that your hard drive may not be fast enough to play back smoothly.
Please share more details of your hardware, video source, workflow
Safe Harbor Computers
>make movies with games
Does that mean you are using screen capture software?
Jing by Techsmith http://forums.adobe.com/message/3692768
Read Bill Hunt on a file type as WRAPPER http://forums.adobe.com/thread/440037
What is a CODEC... a Primer http://forums.adobe.com/thread/546811
What CODEC is INSIDE that file? http://forums.adobe.com/thread/440037
Report back with the codec details of your file, use the programs below... a screen shot works well to SHOW people what you are doing
If you have a red line over the timeline after importing a video and before adding any effects... your project is wrong for your video... read above about codecs
Once you know exactly what it is you are editing, report back with that information... and your project setting, and if there is a red line above the video in the timeline, which indicates a mismatch between video and project
H.264 will NOT work inside an AVI wrapper http://forums.adobe.com/thread/854115
More information needed for someone to help... click these links and provided the requested information
For CS5 and later, the easy way to insure that your video and your project match
See 2nd post for picture of NEW ITEM process http://forums.adobe.com/thread/872666