The MBT Monster Flame Light produces a realistic effect of a large flame, but it is totally harmless as the effect is actually made by amber and blue light bulbs projecting onto a sheet of silk that is blown by a fan. The below video gives you a view of how this looks in practice.
This product is extremely popular for theaters that need a flame-like effect for theatrical productions without risk of fire. It's also great for party rooms and general decoration where a natural lighting effect is wanted.
For Halloween and parties, also check out some of MBT's smaller flame light products, which are smaller and less expensive.