how can i use world dance floor in just dance 2014 or 2015?
You need a custom build (latest development build or at least 4.0.2 merged with wiispeak) or a build from Ishiiruka branch. Then, you
dump the required certificates and World Dance Floor starts working...
i dumped certificates and get newest dolphin build but it still does not work. i tried with ishiikura branch.
it works but it is slow and sound lags. it is not playable.
Your computer is too weak to handle these games then. Here, both games works flawlessly at full speed all time...
what is difference between official dolphin and ishiikura dolphin?
how i can merge it?
Ishiiruka Dolphin is a fork made by some developers including some legacy features (like DX9). At current state, Ishiiruka is too different from development builds, you can merge both but you'll need to solve a lot of conflicts, etc. to get it compiling. If you just want Just Dance 2014/2015 support, grab the source from the latest development version at GitHub and merge it with wiispeak branch, it's a lot easier than merging Ishiiruka into master...
Some people said that certificates does not work because servers have some kind of shield with they can block computer. I know that nobody can not speak about older dolphin versions but some guys i asked said that they can not get online games working on newest dolphin version but can on dolphin 3.5.
Is this have some kind of closing Nintendo servers
World Dance Floor from Just Dance 2014/2015 still works, apparently Ubisoft uses their own servers...
But what is with Dolphin version?