```chris@debian:~$ sudo apt-get install vokoscreen
[sudo] password for chris: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  python-pyqt5.qtsvg python-pyqt5.qtwebkit python-qtpy
Use 'sudo apt autoremove' to remove them.
The following additional packages will be installed:
  ffmpeg libavdevice57 libavfilter6 libcdio-cdda1 libcdio-paranoia1
  libdc1394-utils libebur128-1 libpgm-5.2-0 librubberband2 libsdl2-2.0-0
  libsodium18 libzmq5
Suggested packages:
  ffmpeg-doc
The following NEW packages will be installed:
  ffmpeg libavdevice57 libavfilter6 libcdio-cdda1 libcdio-paranoia1
  libdc1394-utils libebur128-1 libpgm-5.2-0 librubberband2 libsdl2-2.0-0
  libsodium18 libzmq5 vokoscreen
0 upgraded, 13 newly installed, 0 to remove and 0 not upgraded.
Need to get 2,458 kB/4,925 kB of archives.
After this operation, 10.2 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Err:1 http://security.debian.org/debian-security stretch/updates/main amd64 libavfilter6 amd64 7:3.2.11-1~deb9u1
  404  Not Found [IP: 2a04:4e42:e::204 80]
Err:2 http://security.debian.org/debian-security stretch/updates/main amd64 libavdevice57 amd64 7:3.2.11-1~deb9u1
  404  Not Found [IP: 2a04:4e42:e::204 80]
Err:3 http://security.debian.org/debian-security stretch/updates/main amd64 ffmpeg amd64 7:3.2.11-1~deb9u1
  404  Not Found [IP: 2a04:4e42:e::204 80]
E: Failed to fetch http://security.debian.org/debian-security/pool/updates/main/f/ffmpeg/libavfilter6_3.2.11-1~deb9u1_amd64.deb  404  Not Found [IP: 2a04:4e42:e::204 80]
E: Failed to fetch http://security.debian.org/debian-security/pool/updates/main/f/ffmpeg/libavdevice57_3.2.11-1~deb9u1_amd64.deb  404  Not Found [IP: 2a04:4e42:e::204 80]
E: Failed to fetch http://security.debian.org/debian-security/pool/updates/main/f/ffmpeg/ffmpeg_3.2.11-1~deb9u1_amd64.deb  404  Not Found [IP: 2a04:4e42:e::204 80]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?
chris@debian:~$ 
```