It probably depends on the software you are using and the video format. Basically you need to capture less frames per second or use a smaller resolution. It might also be possible to use different software to compress the footage after the fact but still it would be reducing resolution or frames.
But quite honestly, 25mb is basically nothing, maybe 2 or 3 minutes so you may want to consider a better method of distributing your files, for example upload them to a file store (hugefiles, billionsuploads, etc) and then just email the link.