Slow motion Tesla Coil recordings of SSTC sparks. Recorded at 8000 frames per second and replayed at 15-30 frames per second. Notice the step leader, known from natural lightning strikes and the hot spots that might be forming from collapsing plasma channels.
Join the discussion at High Voltage Forum about these high speed video recordings and their slow motion playback: https://highvoltageforum.net/index.php?topic=2280.0