If it's an .mp4 or .gif then just attach it in the 'Select/drop/paste' box below. If it's a playable video on another site, then go down to the 'Show post options' dropdown and paste the link there.
If it's an .mp4 or .gif then just attach it in the 'Select/drop/paste' box below. If it's a playable video on another site, then go down to the 'Show post options' dropdown and paste the link there.