I need help with a bug

I wanted to give my Brush a texture like like in Crash Video and it doesnt work, I have no idea and can i get please get some help? And when i load the map I only see the void.

 

can you give us more detail? what method are you trying?

 

I tried a dev texture from tf2 and used the same method like Crash in his Video did

 

make sure your camera can view textures. To do this click on then set it to 3d Textured 2

 

Thank you my Problem is solved

 

Also, for future reference, the more accurate your post is, the better help anyone can give. Crash has made maybe 100's of videos and if you say "just like in crash video", its not exactly easy to know which one. We're not mind readers, so please explain it like everyone knows.