I have a movie that has around 794 MB is there any way of compressing the file so that it will fit a 700MB CD-R?
Yes. If you want a better answer you will need to provide information about the type of file you are starting with and what type of file or format you want to end up with.
I can't just tell you a single simple way to compress. It will take some reading and learning and experimenting. Did you read the VirtualDub Help file? You can use VirtualDub to change the video resolution or the video and audio codecs used or the bitrates used by those codecs. You probably do not want to change the video resolution but for example you might try lowering the audio bitrate. That can often make a file much smaller. I don't know what audio codec is being used but if it is not MP3 then you may want to change to a MP3 audio codec. You could also change the video bitrate. Or you could use a combination of both. You want to probably just lower the audio or video or both bitrates just enough to make the output size just small enough to fit the disc. This will just take some experimentation. See this guide. Look especially at the Processing It section where it shows how to set and change video and audio compression. http://nickyguides.digital-digest.com/vdub-filters.htm You can find many other guides by just doing a web search for Virtualdub Guides.
is there anything faster? using VirtualDub is time consuming, is there a faster way to compress 794 MB, so that it will fit a 700MB CD-R without cutting out some of the movie parts?