SESAC (formerly known as the Society of European Stage Authors and Composers) is one of the major performance rights organizations (PROs) in the United States, along with ASCAP (American Society of Composers, Authors, and Publishers) and BMI (Broadcast Music, Inc.). SESAC's primary role is to collect royalties on behalf of songwriters, composers, and music publishers when their music is performed publicly. This can include live performances, broadcasts, and streaming.
When a video is blocked due to SESAC, it typically means that the music used in the video is protected by SESAC, and they have enforced copyright measures that prevent the video from being viewed in certain countries. This could be due to territorial licensing agreements or copyright restrictions imposed by the rights holders.
If you're encountering this issue with a specific video, it may not be viewable in your country as a result of those copyright restrictions. In such cases, you might try looking for alternative sources or versions of the content, or you could consider using a VPN (Virtual Private Network) to access content from a different region, though be aware that using VPNs to bypass geo-restrictions can have legal or service-related implications.