Demo not working: Unknown lifecycle phase

[McPringle]

In the demo RecordAndEncodeVideo is the file comment mentioning to execute this command line:

mvn install exec:java -Dexec.mainClass="io.humble.video.demos.RecordAndEncodeVideo" -Dexec.args="filename.mp4"

If do this, all I get is a maven error:

[INFO] Scanning for projects...
[INFO]
[INFO] --------------------< io.humble:humble-video-demos >--------------------
[INFO] Building video_demos 0.3.0
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  0.153 s
[INFO] Finished at: 2021-02-13T15:30:24+01:00
[INFO] ------------------------------------------------------------------------
[ERROR] Unknown lifecycle phase ".mainClass=io.humble.video.demos.RecordAndEncodeVideo". You must specify a valid lifecycle phase or a goal in the format <plugin-prefix>:<goal> or <plugin-group-id>:<plugin-artifact-id>[:<plugin-version>]:<goal>. Available lifecycle phases are: validate, initialize, generate-sources, process-sources, generate-resources, process-resources, compile, process-classes, generate-test-sources, process-test-sources, generate-test-resources, process-test-resources, test-compile, process-test-classes, test, prepare-package, package, pre-integration-test, integration-test, post-integration-test, verify, install, deploy, pre-clean, clean, post-clean, pre-site, site, post-site, site-deploy. -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/LifecyclePhaseNotFoundException

Apache Maven 3.6.3 (cecedd343002696d0abb50b32b541b8a6ba2883f)
Maven home: C:\Users\McPringle\.m2\wrapper\dists\apache-maven-3.6.3-bin\1iopthnavndlasol9gbrbg6bf2\apache-maven-3.6.3
Java version: 15.0.1, vendor: AdoptOpenJDK, runtime: C:\Program Files\AdoptOpenJDK\jdk-15.0.1.9-hotspot
Default locale: de_CH, platform encoding: Cp1252
OS name: "windows 10", version: "10.0", arch: "amd64", family: "windows"

I invested a hole working day trying to encode a video without success. A working example would be really great. If you need more information, please ask and I'll happily provide it.