This type of camera usually downloads better with a Firewire (DV) connection. Sony call this "i.Link". Some mini-DV cameras only use the USB connection (if they have one) for stills and can only download video by Firewire. This is because you have to play the tape into the computer, not just copy a file. According to a list on the Sony site, your particular model is not one that can use USB for video transfers to computer.
Most PCs have a USB port, but no Firewire port. Macs often have a Firewire port but may not have USB. As most Windows PCs do not come with this interface, you might need to fit an add-on Firewire interface card. This will come with a driver for the card.
Suitable Firewire (DV) cables can easily be found on Amazon or eBay. You will need the kind with a small (four pin) connector at one end and a larger (six pin) connector at the other.
Sony have a help page for your camera, with tutorials and downloads, at THIS LINK