A question to which I provided an answer has been migrated from ELL to ELL meta. I probably should know why this occurred, but I don't. I am not upset that it has been migrated (I am sure there was a good reason), nor am I asking for this to be changed. However, I would like to know (i) the difference between ELL and ELL meta, and (ii) the sorts of reasons that can cause a question to be migrated.
First things first, the Help Center has an explanation of meta and what it's used for - the short version is:
Meta English Language Learners Stack Exchange is the part of the site where users discuss the workings and policies of English Language Learners Stack Exchange rather than discussing learning the English language itself. It is separated from the main Q&A to reduce noise there while providing a legitimate space for people to ask how and why this site works the way it does.
I migrated the question you answered, because it was an exact duplicate of another question that was migrated to meta, and that question was closed as a duplicate of a question that was already on meta. (Please suggest a good web site where I can ask what is said in a short part of a video?)
Transcription questions are mostly off-topic on ELL. We aren't set up to be a transcription, translation, or writing service. We do however want to be helpful to folks even though certain types of questions don't fit well on the main site, so we stretch the definition of what the meta site can be used for, and sometimes move requests for resources or other similar questions here so we can talk about them without disrupting the main site.
I'm glad that you've found meta, because it is really important that the community voices their opinions on the discussions that happen here. This is where we decide how to apply the general Stack Exchange guidelines in a way that makes sense for ELL, fix issues like questions that may have been too hastily closed, or ask for help understanding why something happened the way it did.