You'd need a huge battery to power a camera for that long, as well as enough storage to match.

Let's assume something at the low end of the quality scale, e.g. 1Mbps 480p H.264; that's 125KB/s, or roughly 11TB for 3 years of video. Likewise, take 5W as an average power consumption. 5W for 3 years turns out to be around 130kWh, which is a large capacity even for an EV battery. For comparison, the largest Tesla has 100kWh.

Have you seen the movie Contact? Like that but in reverse

They don't, they think the camera fell off the seal.

My read of this article is that the camera was only turning on for short periods, basically sparse samples of time.