i may be stupid but how tf do you get videos/media from other sites to actually embed in your post instead of just displaying as a link

30 | Game Designer(?) | Arcade Lover | KOF Hippie™ | Ascended & Unhinged Sonic Fan | Sudden Onset Touhou Fan (it's terminal)
i may be stupid but how tf do you get videos/media from other sites to actually embed in your post instead of just displaying as a link
I've had success with putting two line breaks after the link instead of just one