First, I apologize for my bad English! I'm doing the best I can.
Svtplay-dl is called by my program (streamcapture2) using absolute path. svtplay-dl, in turn, calls, if necessary, ffmpeg. Svtplay-dl looks for ffmpeg in $PATH. It could have been possible to place svplay-dl in $PATH and let streamcapture2 look in $PATH.
All programs, including streamcapture2 are static. In the case of streamcapture2, I use Qt5, and Slackware still uses Qt4. So to allow streamcapture2 to be statically compiled, I do not need to send a lot of library files.
I attached ffmpeg because the user Should not be forced to think about installing the latest version. If you install the Slackware package from slackbuilds.org you get version 3.2.4 so my version is also a bit newer. The system will first look in /usr/local/bin and find the latest version.
As for ffmpeg10-bit (ffmpeg uses 8-bit) then I have to admit I do not know if it's needed.
bash-4.3$ /usr/bin/ffmpeg -version
ffmpeg version 3.2.4 Copyright (c) 2000-2017 the FFmpeg developers
built with gcc 5.3.0 (GCC)
configuration: --prefix=/usr --libdir=/usr/lib64 --shlibdir=/usr/lib64 --docdir=/usr/doc/ffmpeg-3.2.4/html --mandir=/usr/man --disable-debug --enable-shared --disable-static --enable-gpl --enable-version3 --enable-avresample --arch=x86_64 --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-gnutls --enable-libcaca --enable-libcdio --enable-libssh --enable-libtheora --enable-libv4l2 --enable-libvorbis --enable-libvpx --enable-opengl --enable-libopenjpeg --enable-libpulse --enable-libsmbclient --enable-libwavpack --enable-x11grab
libavutil 55. 34.101 / 55. 34.101
libavcodec 57. 64.101 / 57. 64.101
libavformat 57. 56.101 / 57. 56.101
libavdevice 57. 1.100 / 57. 1.100
libavfilter 6. 65.100 / 6. 65.100
libavresample 3. 1. 0 / 3. 1. 0
libswscale 4. 2.100 / 4. 2.100
libswresample 2. 3.100 / 2. 3.100
libpostproc 54. 1.100 / 54. 1.100
bash-4.3$ ffmpeg -version
ffmpeg version 3.3.2-static
http://johnvansickle.com/ffmpeg/ Copyright (c) 2000-2017 the FFmpeg developers
built with gcc 5.4.1 (Debian 5.4.1-11) 20170519
configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc-5 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gray --enable-libass --enable-libfreetype --enable-libfribidi --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libzimg
libavutil 55. 58.100 / 55. 58.100
libavcodec 57. 89.100 / 57. 89.100
libavformat 57. 71.100 / 57. 71.100
libavdevice 57. 6.100 / 57. 6.100
libavfilter 6. 82.100 / 6. 82.100
libswscale 4. 6.100 / 4. 6.100
libswresample 2. 7.100 / 2. 7.100
libpostproc 54. 5.100 / 54. 5.100
Ingemar Ceicer