I've started leaving my webcam on as a motion detector to find out who is leaving the shopping cards on our lawn, and ultimately have found it useful to stitch the images together into a movie. There are several ways to do this - and my way maybe isn't the best - but it works for me.
I first installed and configured motion, which I've used for years. I then created a file in ~/.motion called motion.com:
$ cat ~/.motion/motion.conf
height 480 width 640 framerate 2
By creating this file, it allows me to start motion without modifying the global motion.conf file permissions, or *gasp* running it under sudo. There are lots of options you can put in your motion.com file.
With motion installed, and configured, now install mencoder.
I prefer to generate a seed file based on the creation date for each image. If you try to use mencoder with just a *.jpg, it works, but my video jumped around.
$ pwd /home/path/Desktop/motion $ ls -rt *.jpg > list.txt
This list.txt file now has the filenames, in chronological order, ready for consumption. I create the video like so:
mencoder mf://@list.txt -o `date +%G%m%d`.avi -ovc lavc -lavcopts vcodec=mjpeg
This will output a file with today's date in a few seconds. Remember, the `'s are the key by the #1, not quotes.