Once the desired gif files are generated, the individual frames can be combined into a single MPEG file using one of several publically available encoders.
When generating the gif files, remember that MPEG files can grow very large, so you will probably want to specify a smaller output size than the default for the GF driver.
Tips for animations:
MPEG loop of ETA surface pressure
Script to create ETA gif images
Script to create ETA animation from gifs
MPEG loop of IR satellite images
Script to create satellite gif images
Script to create satellite animation from gifs