If the DVDs need an mpg file,

If the DVDs need an mpg file, then rendering to one format then re-rendering involves quality loss and time – I’ve never come across VLP files – the only ones with that extension I know about are old text files for karaoke – I don’t suppose this is why there is no video? One clue would be file size – is it a huge file or a small one. vlp files are tiny. Are you sure you exported it as a video file and not accidentally produced a text file instead?