can't build on linux

i download sourse from github -> unzip -> run autogen.sh -> type sudo ./configure

...
checking whether we are using the GNU C++ compiler... yes
checking whether g++ accepts -g... yes
checking dependency style of g++... gcc3
checking for ranlib... ranlib
checking for selective static linking... -Wl,-static ... -Wl,-dy
configure: Configuring ffmpeg. This is quiet and takes a bit. Be patient.
yasm/nasm not found or too old. Use --disable-yasm for a crippled build.

If you think configure made a mistake, make sure you are using the latest
version from Git. If the latest version fails, report the problem to the
ffmpeg-user@ffmpeg.org mailing list or IRC #ffmpeg on irc.freenode.net.
Include the log file "config.log" produced by configure as this will help
solve the problem.
configure: error: ffmpeg configuration failed.


so i downloaded ffmpeg sourse from github and move bundle/ffmpeg folder
but still i can't build stepmania 5

how can i fix it?
and
I ask this problem in FFmpeg?

There's no reason to build stepmania as root. Don't use sudo.
Find the yasm package for your distro and install it. Under debian, this is the "yasm" package.
Also, you shouldn't replace the bundled ffmpeg with ffmpeg from anywhere else.

Thank You, You've been a great help.