For a good weld MIG requires a cover gas. The video shows the fume extractor works but what about weld quality? In outdoor MIG welding the wind can be a problem and care is taken to shield the weld area. In schools the fume hood is usually quite far from the work allowing the shielding gas enough lag time to be effective. Have you experimented with different distances or is your flow so low as to not have an effect on weld quality. Very nice video and great idea. Thanks for sharing.