Guy looked like he was lifting a TV or something.....was this lack of safety features on devices or cheap
batteries maybe?
Need more details to make a hypothesis.
Many battery explosions or fires are caused by carrying naked batteries in a pocket. Contact with coins or keys creates an electrical circuit causing the battery to release its energy and vent (hot gas) or go into thermal runaway (flames or explosion).
Solution: Always carry loose batteries in a plastic battery case.
Using a "direct battery" or "hybrid-top" mechanical mod with a juice attachment
without an extended center pin will cause the battery to hard short with similar results to the above.
Solution: Know how to operate your particular battery device safely and use the proper juice attachment on it.
Continuous pressure on the fire button can cause a rapid over-discharge of the battery resulting in venting, fire, or explosion.
Solution: Deactivate the fire button when not in use.
Keep your batteries in "like new" condition.
Solution: Inspect the insulating wraps and insulator rings for tears, holes, or other defects. Either re-wrap or replace damaged wraps/rings or discontinue using the battery.
Transporting any battery device in a pocket or purse without first disabling the battery can result in a bad day.
Solution: If a regulated mod, turn the mod off during transport. If a mechanical mod, lock the fire button or remove either the juice attachment or battery.
Batteries are the most important piece of gear in our setups, so it makes good sense to buy the best available no matter the cost. Its not worth it to save a buck or two on an off brand, "re-wrap" brand. Brands like Lg, Samsung, or Sony are of better quality than the off brand batteries.
There is no such thing as a completely "safe" battery. They all have the potential to be dangerous if misused or abused.
Battery Basics for Mods: The Definative Battery Guide for Vaping
Deeper Understanding of Mod Batteries Part 1
Are You Using a "Rewrap" (Rebranded or Aftermarket) Battery?
A Beginner's Guide to Your First Mechanical Mod