From your question it is not clear whether the problem is due to lack of memory access or because videoReader has problems opening the file due to its size or fps. If you post your code, it will clarify.
If you have a large amount of data to process, then dont read the full file into memory, but process it by blocks (frames are common block sizes for video).
first advice to you is this however. Compress the video using a lossless encoder. Let me recommend lagarith, as i have used it myself for scientific applications.
If the problem is somehow connected to the fps, then simply change it for your files. Use the program ffmpeg for this, has a great command line interface.
If the problem is the size of the video files (even more doubtful) use ffmpeg once more to split your files into smaller ones.