Export as mpg to give you a standard video format for conversion.
If you do not have one there are many freeware converters available on the Internet of variable quality - the most popular one here is a program called Super available here http://www.erightsoft.com/SUPER.html
There is no option to create the FLV files as the original poster requires, and me too, as far as I can see it compresses the video using the same codecs as Flash player requires but does not put it in a FLV container file.
Changing the file extension to FLV either before or after export does not work as the file headers still say it is a mp4 format.
Until Magix include FLV as an export format I think we are stuck with converting externally.
The only way is to create any file format like mp4 or avi or mpeg and use a converter. One i use in the past was MOVAVI software (low price I think $19) also NCH software search on the web you can fiound many software to convert your file.