Assume RHEL 5, 32bits :
mkdir lib && cp libavutil.so.50.40.0 lib/ && cd lib/ &&
ln -s libavutil.so.50.40.0 libavutil50.so
ftp://ftp.pbone.net/mirror/atrpms.ne...2.el5.i386.rpm
( Unpack with :
'rpm2cpio libavutil50-0.6.1-42_git20110322.el5.i386.rpm | cpio -idmv'.)
export LD_LIBRARY_PATH=/home/<?>/lib:/usr/lib:/lib && ./blender ,
to see, if you now have got the right library.
..