My guess - It sounds like your MacBook Pro is syncing your Photos/Videos to iCloud, which is normal on a new computer. If you open the Photos app, and in the left pane click Photos under library, and scroll to the bottom, you may see some sort of message like "Updating", or "downloading xxx photos", etc. Note this only happens if the MacBook Pro is plugged into juice and on WiFi. “com.apple.photos.VideoConversionService” is doing exactly what it describes – any videos that aren’t in a compatible format for iCloud are being converted in the background while you’re trying to get other work done.
This will all go away once your Photos (which includes Videos) are sync'd. For me it took about 2-3 days (it does it in the background so it can take longer if you are using your MacBook Pro a lot of the day). I have about 100 videos and 20,000 photos.