First, find the YouTube video that you want to share. Go to the video's YouTube page.
Copy the URL of the video from the address bar in your web browser. You can do this by selecting the entire URL and pressing Ctrl+C on a Windows computer or Command+C on a Mac.
Next, go to the forum where you want to add the video. Look for the "Add post" or "Reply" button and click on it.
In the text editor of the forum, click on the "Insert media" or "Insert video" button. This button may look like a film strip, a play button, or a camera icon.
Paste the YouTube video URL that you copied earlier into the designated field.
You may also be given the option to adjust the video size or alignment. Make any desired adjustments and then click the "Insert" or "Save" button.
Preview your post to make sure the video is embedded correctly.
Finally, click the "Submit" or "Post" button to publish your forum post with the YouTube video.
Note that some forums may have different steps or requirements for adding videos. If you are unsure, you can check the forum's guidelines or ask a moderator for assistance.