The CU-VD3 is your best choice.

When the CU-VD50 is connected to the GZ-HD300, it creates what are called AVCHD discs. These are true high definition discs created using standard DVD-R media. They can playback in most recent Blu-ray players which have the AVCHD logo, including all 2009 JVC Blu-ray players. This is the only option using the CU-VD50 directly with the camera. The other option you have is to use the provided CD-ROM software which came with your JVC camera. This works with virtually any recent Windows computer with a DVD-Burner. This allows you three options: #1. You can create a tru Blu-ray disc if you have a Blu-ray burner. #2. You can create an AVCHD disc using the DVD burner on your computer. #3. You can down-convert your HD video to standard definition and create a regular DVD using your computer's DVD burner.

The CU-VD3 will make AVCHD discs that will play in Blu-ray players in true high definition. It will not make standard DVD's. To make standard DVD's your best bet is a JVC DR-MV80 or DR-MV150 DVD Recorder. You can use the A/V output on your GZ-HD300 to connect to these DVD recorders and make high quality standard DVD copies.

You cannot burn DVD's to a CU-VD3 or CU-VD50 with a GZ-HD7. You can only burn HD Data discs as there is no conversion from High Definition to Standard Definition. Fortunately, there is a different solution. You can connect your GZ-HD7 to a DVD Recorder, such as the JVC DR-MV80B or DR-MV150B. You simply use the Yellow (Video), White & Red (Audio) connectors from the camcorder to the DVD recorder. I think you will be happy with the quality.

Yes, GZ-MG680 is compatible with a CU-VD50 Share Station.