Methane can be detected by optical spectrometry. Since methane is not only a pollutant but also a very potent green house gas (30x stronger than CO2), efforts are made to map the sources from the air and space [0-2].
Edit: I found the FLIR camera shown in the video. It is made for gas emission analysis: https://www.flir.com/products/flir-g-series/
[0]https://www.optica-opn.org/home/newsroom/2022/february/mappi...
[2]https://www.jpl.nasa.gov/news/nasa-mission-excels-at-spottin...