You can replace replace "libffmpeg7_v19.so" in install directory for me "/data/data/com.bsplayer.bspandroid.full/nlibs/" by the file you downloaded.
In"Terminal Emulator" or "adb shell"
It's look like this :
Command mode :
shell@remix_x86_64:/ $su
root@remix_x86_64:/ #cd /data/data/com.bsplayer.bspandroid.full/nlibs/
root@remix_x86_64:/data/data/com.bsp...oid.full/nlibs #mv libffmpeg7_v19.so libffmpeg7_v19.so.ref
root@remix_x86_64:/data/data/com.bsp...oid.full/nlibs #cp /sdcard/Download/libffmpeg7_v19.so ./
root@remix_x86_64:/data/data/com.bsp...oid.full/nlibs #ls -als
total 24088
-rwx------ u0_a82 u0_a82 781820 2016-08-06 13:13 libBSPlayer16_v19.so
-rwx------ u0_a82 u0_a82 363024 2016-08-06 13:13 libbspmplay2l1_v19.so
-rwx------ u0_a82 u0_a82 132456 2016-08-06 13:13 libbspmplayl1_v19.so
-rwx------ u0_a82 u0_a82 255308 2016-08-06 13:13 libcpdmod2_v19.so
-rw-rw---- root root 11685788 2016-08-06 13:20 libffmpeg7_v19.so
-rwx------ u0_a82 u0_a82 11439612 2016-08-06 13:13 libffmpeg7_v19.so.ref
root@remix_x86_64:/data/data/com.bsp...oid.full/nlibs #chown u0_a82:u0_a82 libffmpeg7_v19.so
root@remix_x86_64:/data/data/com.bsp...oid.full/nlibs #chmod 700 libffmpeg7_v19.so
root@remix_x86_64:/data/data/com.bsp...oid.full/nlibs # exit
shell@remix_x86_64:/ $ exit
Restart BSPlayer
