I installed free copy of ALLvideos and enable the extension in joomla 2.x & 3.x; When i open my article i cant see the "Allvideo" media button at the bottom of articles. Please what did i do wrong. I will see "DJ media tools, article, image, page break, read more, etc

Hi. There is no button. You have to write the tag on your own. Read the documentation page at www.joomlaworks.net/support/docs/allvideos to see all the supported media types.