For Chrome, Edge and Safari on a Mac or a PC. While you watch something on YouTube, click the button and the clip maker opens with that video, the start already marked at the moment you were on.
It's the strip of links just under the address bar. If you can't see it:
Chrome
Press Ctrl + Shift + B on a PC, or ⌘ + Shift + B on a Mac. Or: the ⋮ menu → Bookmarks and lists → Show bookmarks bar.
Edge
Press Ctrl + Shift + B on a PC, or ⌘ + Shift + B on a Mac. Edge calls it the favorites bar. If it asks, choose Always.
Safari (Mac)
Press ⌘ + Shift + B, or choose View → Show Favorites Bar.
2. Drag the button onto the bar
Press and hold on ✂ Clip to EC-OS above, drag it up onto the bar, and let go. That's it.
Clicking the button on this page just says "Open a YouTube video first." That's normal: it only works on a YouTube video.
If dragging doesn't work
Copy the button's code: Copied
Bookmark this page: Ctrl + D on a PC, ⌘ + D on a Mac. Save it to the bookmarks bar (Edge: favorites bar; Safari: Favorites).
Right-click the new bookmark on the bar and choose Edit (Safari: Edit Address).
Name it Clip to EC-OS. Replace the address (URL) with the code you copied, and save.
If Copy doesn't work, select all of this and copy it yourself:
3. Use it
Play a video on YouTube. Pause or keep playing at the bit you want.
Click ✂ Clip to EC-OS on the bookmarks bar.
The clip maker opens in a new tab with the start marked. Mark the end, check the loop, pick sessions and save.
The first time on each computer the browser warns that the connection isn't private. That's EC-OS's own certificate and it's expected: choose Advanced → Proceed (Safari: Show Details → visit this website). After that the browser usually remembers; if it ever asks again, do the same.