That is quite a significant noise from the bike. Obviously abnormal. The best piece of advise I can give you is that as a new bike, presumably under warranty, the bike shop or online retailer should be helping you solve this issue. I would take the bike back there to them. Have a way to show them the video you linked to in your question since the noise is not always reproducible. Praxis has a 2 year warranty on their products. Working with the bike retailer, contact should be made with Praxis regarding the noise and possible fixes, up to and including replacement (at no cost to you).
Here is the link to the Praxis M30 road crank installation guide that also contains the details of their warranty.
A few things to try prior to the bike shop. Inspect the BB area, making sure there is only one dust cover on each side. Also determine that the drive side has a wave washer between the dust cover and crank. If all seems in place then check that the crankarm fixing bolt in the left crankarm is adequately torqued. The spec torque range for this bolt is 48-52 Newton-meters. That is a significant amount of torque that may be difficult for the average person to achieve with a simple "L" shaped Allen wrench. Especially one that is short. A socket with an 8mm hex head on it used with the appropriate ratchet is probably best. That will also fit on the torque wrench that should be used for certainty.
You can also check the torque of the chainrings bolts (should be between 8-10Nm). I don't believe the chainrings are the source of the noise because there isn't any pressure on the cranks when the sound is heard. It sure seems like the sound is related to a problem in the bottom bracket bearing system.
