The Transitland website and APIs can be used to find many GTFS Realtime feeds. Here's the YRT GTFS Realtime feed you seem to be looking for: https://www.transit.land/feeds/f-yrt~rt

And here are its two source URLs:

• http://rtu.york.ca/gtfsrealtime/VehiclePositions

• http://rtu.york.ca/gtfsrealtime/TripUpdates

As others have already shared, to inspect those GTFS Realtime endpoints you do need to parse them from protocol buffer format. It's binary, so it can't be displayed in a text editor or browser without intermediate processing.

If you want to quickly inspect it, the Transitland website will let you view it as JSON: