The Static-y creature in the house and the ECKVA signal are working at cross purposes
The broadcast interruption for ECKVA5 may have been a warning delivered at the house actually catching the signal to not actually allow whoever cut the signal and left him a message into the house itself, perhaps not noticing it was being recorded elsewhere. And that someone could well have been the creature. That and we haven't seen enough to believe they're cooperating. The two videos after 12 weren't posted by Hawkins.
How could he have posted them? His recording equipment was smashed. Whatever has been sending the signals has taken over the channel. Eckva is implying that the Ark is someplace digital rather than physical.
"Can you help me find the brightest light?" is a reference to Broadcast #5 of Clear Lakes 44.
At the end of the video, the door opens up to reveal a HECKING bright light. Bright enough to supposedly end the video, and bright enough that it's blinding. By "the brightest light", the person is referring to the house from said video.