How to transfer a large video (> 2 GB) from iPhone to a PC?

You can use the program iExplorer. It is free, and you can download it to view files on your iDevice. Simply plug in your phone, open iExplorer, and then on the sidebar, select Photos -> Recorded Videos.

A method which works for me is to use Google Photos and a WiFi network.

I install Google Photos on my iPhone. When the iPhone is connected to a WiFi network, the video automatically gets uploaded to Google Photos.

After the video is uploaded and processed, I can simply download it from Google Photos onto my PC.

The shortcoming of this method is that it can be slow, and it can drain my iPhone battery. For example, it may take 1 hour to upload and process a 5 GB video to Google Photos, though it takes only about 5 minutes to download.