Isn't Moore's law a myth anyway?
Yes and no.
At the beginning, it was a "simple" economical observation by Moore, that with the advance of technology and the prices of the the material and energy, the most economical chip production would double the number of transistors every two years.
Which it actually did, untill a decade or so ago, where, as explained in the video, you had trouble to create the light sources needed to make smaller transistors. We are now so close to actual, physical limitation of the transistor themself (independently of how they are fabricated), that Moore's law will be physically impossible in... a decade I think? anyway, as a transistor would need to be less than a couple dozen atoms wide, in which wase the quatum effects used for making transistor aren't really valid anymore.
So what ASML did is prettty impressive, but it really announced the beginning of the end of Moore's Law (a 13nm light source should permit something around a couple nm bridges width iirc, so a couple dozen Si atoms). I wonder how engineers will circomvent the physicall limitations to still increase the power of the chips, with "brute forcing" by simply increasing the transistor density (like they did with the multi core technology the first time physical limitations were reached).
Video doesn't go into a lot of detail but isn't this inferior to the existing 7nm and soon to come 5nm lithography tech?
They have a 13nm light source. There are tricks to use a light source to etch a structure much smaller than the light source. As they alluded to in the video, current chips (event the 7nm chips I think) are currently produced with light sources around 100nm iirc (or was it 60? anyway, much higher than 13nm). They should be able to go much lower with a 13nm light source, but the probabilistic theories on which transistors are working start to brake down around the nm mark.