UPDATE: THREE WEEKS HAVE PASSED THE DEV HAS NOT PUSHED UPDATES YET I AM LOSING HOPE.
This is a detailed "summarization" of the already open issues.
Almost/All attempts on playing a video on version 5.4 result in the error code: ffmeg 0xfffffffa
And thus soft-locks your app, preventing any video or audio from playing.
this is a critical issue and until fixed, prevents the app from working.
Luma3DS: v13.0.2
ThirdTube: v0.5.4
Credit to @azgaresncf for a solution? "AV1 should be working on the 3DS, as the creator of the original Video player is saying here, because the AV1 decoder of the player (dav1d) is a SOFTWARE decoder, not an hardware one. [...] So the first thing that we can do is to bring the updated video player source code to ThirdTube." [referencing Video player for 3DS by: Core 2 Extreme]
Image from other user (credit to: @0529Cb1)

Info From @SeveringHams:
The error thrown, avformat_open_input() failed -1094995529 seems to be returned/thrown by the demuxer in FFmpeg, just looking at the documentation at https://ffmpeg.org/doxygen/trunk/group__libavf.html
The only mentions of this error anywhere on Google (by searching "avformat_open_input failed -1094995529" WITH the quotes) are on Chinese websites, and the one English translated one says to enable the demuxer library, or indicate in the configuration what demuxer library to use, or something to that effect.
Here is the website I found this on: https://programmersought.com/article/89887525290/ It is under the header "Encounter Problems"
The build.txt file in /library/FFmpeg/ tells us that many features of FFmpeg are configured to be disabled on the custom build of FFmpeg used in ThirdTube, and a handful of formats are selected to be enabled, so perhaps reconfiguring it to enable YouTube's current video file format (whatever it may be) would make it work.
I myself could not figure out how to get it to reconfigure and recompile, so maybe someone more experienced than measly me could crack the case.
UPDATE: THREE WEEKS HAVE PASSED THE DEV HAS NOT PUSHED UPDATES YET I AM LOSING HOPE.
This is a detailed "summarization" of the already open issues.
Almost/All attempts on playing a video on version 5.4 result in the error code: ffmeg 0xfffffffa
And thus soft-locks your app, preventing any video or audio from playing.
this is a critical issue and until fixed, prevents the app from working.
Luma3DS: v13.0.2
ThirdTube: v0.5.4
Credit to @azgaresncf for a solution? "AV1 should be working on the 3DS, as the creator of the original Video player is saying here, because the AV1 decoder of the player (dav1d) is a SOFTWARE decoder, not an hardware one. [...] So the first thing that we can do is to bring the updated video player source code to ThirdTube." [referencing Video player for 3DS by: Core 2 Extreme]
Image from other user (credit to: @0529Cb1)

Info From @SeveringHams:
The error thrown, avformat_open_input() failed -1094995529 seems to be returned/thrown by the demuxer in FFmpeg, just looking at the documentation at https://ffmpeg.org/doxygen/trunk/group__libavf.html
The only mentions of this error anywhere on Google (by searching "avformat_open_input failed -1094995529" WITH the quotes) are on Chinese websites, and the one English translated one says to enable the demuxer library, or indicate in the configuration what demuxer library to use, or something to that effect.
Here is the website I found this on: https://programmersought.com/article/89887525290/ It is under the header "Encounter Problems"
The build.txt file in /library/FFmpeg/ tells us that many features of FFmpeg are configured to be disabled on the custom build of FFmpeg used in ThirdTube, and a handful of formats are selected to be enabled, so perhaps reconfiguring it to enable YouTube's current video file format (whatever it may be) would make it work.
I myself could not figure out how to get it to reconfigure and recompile, so maybe someone more experienced than measly me could crack the case.