Sorry for the trouble here. The red frames represent the missing media from your Rush project. This can be caused if you moved your source media into a new location on your computer or deleted the media.
If either is true, you can try moving the media back to its original location or reimport the files back to your computer. If your files are not reconnected automatically, you can right-click on one of the clips in the timeline and choose "Find and Connect" to manually connect your clips.
Hope this does the trick!