He was based in Southeast Asia, and on his resume it looked like he met all of the competencies we needed -- including English proficiency.
But on the call, I noticed that whenever I asked him a question, he would turn off his camera, pause for 10-20 seconds, answer the question, then turn his video back on.
It turned out that the man was using a translator and really didn't speak any English whatsoever.
I have no idea how he expected to be able to do the job if he had been hired, but I guess he thought it was worth a shot.
In talking with the remote staffing firm, they were extremely apologetic. He had apparently pulled the same trick with them, but they didn't do video interviews, so it was harder to pick up on.