Jaksta

i want the default to flv not mpg. how do i change that?

JMR downloads in the default format for the given protocol the stream is in.  

The most common protocol that results in an mpg file is the HLS protocol.  

You can see the protocol in the captures progress log, which is viewable from the properties dialog for that capture.

The converter can convert to any of the supported formats (automatically if you want) once a capture is complete.

Protocols do change all the time.  HLS is a very popular protocol and used by many sites. 

What sites do you think are still streaming in a protocol that should still result in an flv file (rtmp, hds or http/flv) but are instead mpg?     

The converter is a wrapper around ffmpeg so can convert almost anything.  If you are getting a conversion error provide your debug logs and the site where the file was capture from: https://support.jaksta.com/discussions/topics/6000009063