I made a 3-minute video and rendered it as AVI file. It was nearly 1 GB in size, and that was too long for sending as an email attachment, which I wanted to do. Is there a better (more compressed) format to use?
You probably used the uncompressed (default) template, which results in HUGE files because there's no compression. You might want to consider MP4 using the "iPad" template. This should result in a file somewhere around 60 to 120MB, depending on the bitrate you use.