Fix YouTube embed rendering showing raw URL instead of player

Summary

YouTube embeds are not rendering as embedded players; instead, the raw URL is displayed. The custom HTML render component needs to be updated to handle YouTube URLs properly.

Steps to Reproduce

1. Insert a YouTube URL into a post or comment.
2. View the rendered output.

Expected Behaviour

The YouTube URL should be rendered as an embedded video player.

Actual Behaviour

The raw YouTube URL is displayed as plain text instead of an embedded player.

Environment

Not provided.

Reported by retoor via DevPlace.