Ah, alright got that cleared up by installing
gcc-c++ So for the most part; everything seems fine, including video playback :)
Seems to be an odd sync thing going on though, but not too sure (doesn't seem to be any A/V desync; but timings for hitting arrows seems off; could be that I'm just used to oITG). SIMPLY LOVE also has text that's really tiny for some reason (normal SM5 theme is fine).
Edit: You need to install
joystick-support under F21 in order to get gamepads and the likes working properly (including dance pads going through a PSX-to-USB converter). Before installing that; my gamepad worked "somewhat" (sometimes it'd be fine, other times it wouldn't register hits; oITG didn't detect it at all). Afterwards, both SM5 and oITG saw my adapter and handled the pads without problem.
As for the A/V sync thing; oITG had a Global Offset out the box (I think -0.062 or something). SM5 has a 0 offset out the box. Doing a manual sync on my machine with SM5 gave me a value close to the one oITG had.
And as for the theme; Ultralight works great.
So SM5 on Fedora 21 (i686; actual F21 with GNOME and not a spin) runs great for me, and compiled without problem. The complete dependency list for F21 is:
sudo yum install automake autoconf mesa-libGL-devel mesa-libGLU-devel glew-devel xorg-x11-server-devel libXtst-devel libXrandr-devel libpng-devel libjpeg-turbo-devel zlib-devel bzip2-devel libogg-devel libvorbis-devel glibc-devel yasm-devel pulseaudio-libs-devel alsa-lib-devel make automake binutils-devel gtk2-devel libmad-devel libstdc++-devel gcc-c++ joystick-support
After installing all of that; compiling SM5 (at the time of writing) should be fine (commands in first post), and running it afterwards should be fine as well.