People keep commenting (rightly, mostly) that the limitations of this attack (e.g. the time required to collect enough data and the amount of zoom required) make it impractical. That's likely mostly true right now. But remember this attack is likely to work on new side channels discovered in the future. Another consideration is that commercial cameras are improving at a breakneck speed. As the researchers put it:

"We also raise concern regarding the real potential of video-based cryptanalysis in our days, given existing improvements in video cameras’ specifications. In our research, we focused on commonly used and popular video cameras to demonstrate video-based cryptanalysis (i.e., 8-bit space for a single RGB channel, Full-HD resolution, and maximum supported shutter speed). However, new versions of smartphones already support video footage of 10-bit resolution (e.g., iPhone 14 Pro MAX and Samsung Galaxy S23 Ultra). Moreover, professional video cameras with a resolution of 12-14 bits already exist, 2 Such video cameras may provide much greater sensitivity, which may allow attackers to perform attacks with the ability to detect very subtle changes in the device’s power consumption via the intensity of the power LED. In addition, many Internet-
connected security cameras with greater optical-zoom capabilities than the video camera used in our research (25X) already exist (30X, 36X) and are likely already widely deployed. Such security cameras may allow attackers to perform video-based cryptanalysis against target devices from a greater distance than that demonstrated in this paper. Finally, new professional video cameras for photographers currently support a shutter speed of 1/180,000 (e.g, Fujifilm X-H2.3) The use of such video cameras may allow attackers to obtain measurements at a higher sampling rate which may expose other devices to the risk of video-based cryptanalysis."