I believe if you can see the sample, you will have no problem watching the concert. Mu-mo stream service was also Japan only and it worked fine everywhere.
https://live-on.mu-mo.net/ayu/
海外での利用は可能ですか？
本サービスは日本国内にてご利用いただくサービスです。
The quality of the stream is a lot better than mu-mo, so maybe this is a good thing.