The microSD card is only a storage medium, you can put any type of file on there. Whether or not the divx can be played is depending on the software, hardware of the phone, more than likely at minimum you may have to convert the video to a compatible format.
A microSD card is only a storage device. You can't play media off of it. I'm not sure the Rumor2 could play DivX videos (more than likely .avi) videos without being converted to another format 1st. I'll say no & that it should be converted to something like .mp4 1st.