Can't open YouTube links from sidebar docs

[microbit-matt-hillsdon]

Describe the bug
YouTube links from sidebar docs, e.g. for "show LEDs" open in a tab that fails to load YouTube.

Based on the message from Safari and the note in the Chrome network tab, this seems to be due to the cross-origin opener policy.

The links work if copy pasted into a new tab.

To Reproduce
Steps to reproduce the behavior:

1. Go to the editor
2. Add a "show leds" block to the workspace
3. Right click on the block, Help
4. Scroll in sidebar docs to the callout where the "LEDs" text is a link to YouTube
5. Click and note you get an error

Expected behavior
YouTube works.

Screenshots
Safari:

Chrome:

micro:bit version (please complete the following information):

N/A

Desktop (please complete the following information):

• OS: macOS
• Chrome 133.0.6943.98 (Official Build) (arm64)
• Safari Version 18.3 (20620.2.4.11.5)