I just imported and older MP4 and only the video plays back at about half speed, even if I keep or change existing sequesce settings. Thanks Ahead.
Where exactly did you get the clip?
Premiere Pro is designed around standardized camera media. Using Internet downloads, you take your chances on whether or not it will work.
You might try a consumer editor, which can be more forgiving of non-standard media. Or you can try conversion to something PP likes. I use this with good results.