If your source is an mpeg2. Then just change the extension from .mpg to .m2t. This works fine in most cases. If the source is any other format. Then drop onto the Vegas timeline. Render to Mainconcept Mpeg2 and choose HDV templates. They all result in .m2t files. Alternately you can even render to MPEG2 raw and then manually change the extension since m2t's are nothing but a different container extension for mpeg2. But if its going back to hdv tape etc then the file should match hdv norms meaning the bitrate has to be within 25mbps. But you can render a m2t with higher bitrates for different applications thereby breaking the HDV standard limits. m2t's are just mpeg2 transport streams.