Maybe, it’s likely a blend of movements. The elbow looks like more of a mechnical function to allow him to hit the larger chords. There is no chugging going on here. Chugging generally refers to repeated 8th notes/16th note downstrokes, usually on power chords - common in metal, hardcore, metalcore, and so on. He is rapidly tremolo picking what appears to be sextuplets that are absurdly tight between the larger chords at approximately 150 beats per minute, equivalent of around 225 BPM 16th notes. His strategy seems to be using the chords as landmarks for chunking purposes, which is about as commonplace as it gets for this genre. It’s a great mental strategy.
Anyways, there’s nothing wrong with elbow movement, but its development is nuanced and as I’ve said above, I’d advise against “muscling through it” to get the action happening. People who tell you to “start out tense” and then relax later on generally do not understand the difference in the neurological process of unnecessary muscle recruitment as a result of acquiring a motor skill (which eventually does go away) versus the alternative, which is where the player actively decides to tense up the muscles in question as a result of a lack of control (what Martin Miller calls “false technique”). In the latter case, because the cerebellum is a non-judgmental portion of the human brain, it assumes the programmed muscular tension is a desired mechanical outcome. It thus never “goes away” because you’ve told the body to program it in. If it feels tense and shitty from the start, it will feel tense and shitty 6 months down the line. So make sure you always feel relaxed with this elbow motion if you’re serious about developing it.
A post I’ve written on this that might help: