(If I tried this, I'd last about seven seconds before detecting the odor of smoke. Then I'd burst into flames and perish.)
This is a viral stunt by Nike, sure, but it appears to be a real part of Brown's offseason training. Brown's trainer, Cara Troutman-Enseki, explained the forearm side-plank thusly on Nike's website:
"It works his entire core -- the transverse and rectus abdominis, external and internal obliques and erector spinae -- as well as the traps, delts, rotator cuffs, rhomboids, pecs, serratus anterior, glutes, quads and adductors."
That is hard-core core work, folks. Careful out there.