Avidemux, a free, open-source video editor, can perform a variety of simple video editing tasks, including compressing videos. You can load a video into Avidemux, select a new codec and set a desired file size. Avidemux re-encodes your video into the new codec, shrinking it to the desired file size so you can fit it on a CD or other removable device, or even send it over the Internet. The compressed video file won't be as high-quality as the original video file, since it's being re-encoded.
Open a video file in Avidemux by clicking the "File" menu and clicking "Open," then browsing to the video file on your computer and double-clicking it.
Click the drop-down box reading "Copy" under Video in the sidebar and select a video codec such as "H.264" from the list.
Click the "Configure" button in the Video section.
Click the "Encoding Mode" drop-down box and select "Two Pass - Video Size" in the list.
Type the size you want the compressed video to be in megabytes into the "Target Video Size (MB)" box.
Click the "File" menu, point to "Save" and select "Save Video."
Type a name for the compressed video file and click "Save."