Gaps are legitimate price levels to look as a support or resistance. The theory is that needs to be gap filled, but I currently believe it's an easy entry/exit trade for those who can move the market. I don't think there is sound analysis behind the why, but it is real.
This image below doesn't have the additional line but shows VPVR with developing VA (value area) on to show how the VA may pull price into it. If you believe that's why, anyway.
The correct picture
There is an option to only have it plotted for the weekend. This helps make the indicator cleaning when there are no trades on a low timeframe. This can be problematic for Friday/Monday holidays where CME is closed, so it is off by default.
The other option selects chart or CME price source, with chart on by default. This means that the price when CME closes for the week would be based on the chart currently being viewed.
Bitcoin Core jar: 1Nam3db9hNMDNNxKMj4uypj9Hxh4oUfHEK
Sorry if I haven't replied to your message yet, I'm a bit backlogged :)