Here's a little tutorial if you encounter this problem.
1/ Select the video you wish to embed on utube to here
2 / Press the embed button under the video , this will show the URL or embed code for the video...copy it.
3 / Open up the section of the board you wish to embed in .....open new topic.
4 / To the left of the screen you will see "Insert :You Tube.......click to open.
5 / Now you will see 2 white boxes , one says insert video title ,the other says insert video referance ...........paste in the embed code to "insert video referance" (the lower box)
6 / Tap in anything to the top box ......for example "a"...............then click ok.
7 / Next you will either see the video you chose in a box on your post ............OR YOU WILL SEE A WHITE BOX !
8 / If you have the white box , this next step will cure the problem .
9 / Look at the "insert video reference" box ,and delete these ive have done a strike through through
10 / Press ok , and your video will be seen .