One of the commenters has an interesting suggestion:

you should also have dry ice covering all sides.. the top was not cooled at all …. ( the thermal conductivity of the material surrounding the diode is not good. 🙂 nex time submerge it in dry ice and just leave enough space for the beam. or add some water … ( wont hurt the diode ) …

Also in the video his partner says DO NOT have the propane tank in the site of the laser.  He agrees 🙂

Here is more about general laser properties from wikipedia:

Lasers are distinguished from other light sources by their coherence. Spatial coherence is typically expressed through the output being a narrow beam, which is diffraction-limited. Laser beams can be focused to very tiny spots, achieving a very high irradiance, or they can have very low divergence in order to concentrate their power at a great distance.

We hope you enjoy the video and are inspired to be scientific and ask questions as well es experiment safely!