These instructions are for embedding the item within a post.
If the video is from youtube, you can enclose it with:
[youtube]url to the video on youtube[/youtube]
For images, including charts, etc., you need to upload the image to a hosting facility such as flickr, imageshack or many of the other free image hosting sites. Then enclose the url with:
[img]url to the image on your host site[/img]
There is a way to do the same thing for embedded flash video using
[flash]url to the swf file[/flash]
but I am not always successful at getting this one to work.
You also have the ability to embed photo slideshows, videos and music dashboards on your profile page. You can see examples of it on my profile page.
That's discussed here:
Photos, Music and Video on your profile