Excellent video. Looks like it’s leaking where he steam tap joins the steam arm assembly.
Now… I’ve never done this before, so take with a pinch of salt. But if I had to do it:
- loosen the steam arm (nut accessible from outside the machine);
- undo all the nuts around the steam tap (one which joins the spindle controlled by the knob and the other which is the inlet of steam;
- pop out the hose coming from the 4-way connector.
This should now allow you to undo the steam tap and hopefully clean all around it, ptfe tap it all and put it back together.
Sadly I can’t be more precise than this due to the lack of technical terms in my vocabulary and experience.
Dave or someone else might be able to help you more.
I wouldn’t use the steam functionality of the machine until this is sorted out (I.e.: operate it in ECO mode).