My guess is that you used screen capture tools to create your source media…
as such…your media has a custom resolution, format and compression scheme….
you likely dropped this media into a timeline that conforms to some video standard (like DV NTSC for example)…
this means that you’ll get red bars when pacing your footage in the sequence…because your media doesn’t matche the resolution sequence…it also means that when the the sequence renders, it’s rendering based on it’s resolution, not the resolution of the source media…
if you select one of your clips in the project panel…it will give you a basic idea of the resolution and Frame rate of the source file…
use this info to create a sequence that matches as closely as possible those parameters…then try editing with that….
Finally…where is this video going? You should be conscious of the final destination format…that can help you create a proper deliverable….
hope this helps….
Alex