It's 4th of July time at the Aperture Science Enrichment Center! (Note: No Weighted Companion Cubes were harmed during the making of this film...)
BTW, this film brought to you by the ultra-cool custom level for Portal called "Weighted Companion Cube Map" by MrCow (hosted by myApertureLabs.com)
The map contains some anti-gravity beams that are part of the puzzles of the level - it's really quite cool. Download it and enjoy - I highly recommend it!