I agree that we need a bigger collection. I also agree with your assessment on text-to-speech voices. We are looking at improving both.
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Well, that's good to hear.
It seems though, that the shutterstock original library is way different from yours, because when I typed "sad" in their music library lots of results came up, whereas yours only one as mentioned earlier.
Also, I did a search comparison for videos as well, and they do not match, it feels almost that you are on some kind of lower tier plan in their API.
I am sure if you combine multiple stock media APIS will you get good result.
For example, on the storryblocks website I searched for running dog in the beach" I got tons of results that exactly match the criteria, where as in your case I only got a few of the correct matches and other ones were just a dog's and video.

I am thinking in investing in tier 3, but I am hesitant because of the library limitations. You said that you have enterprise customers so it seems to me that you could actually afford a higher end APIs, but by the looks of it doesn't seem to be the case.
I checked out the storryblocks API and according to the information, you get same content as they are offering it themselves, which is a lot and is good quality. By the numbers it is way lower than shutterstock but on their website I can find exactly what I need.
You see in my eyes this platform could become truly unique, if it combines high end APIs, it would truly save time and costs of course.

Can you offer any comments regarding my thoughts above? I would really appreciate the transparency and some thoughts regarding the upcoming improvements and priorities, so that way I know what I am investing in, because as it is right now it feels quite limited.
I am hoping you're going to offer audio podcast transcriptions as well, I would use that kind of service for making my podcast trailers. I am a bit confused if you can transcribe video, why not do it with audio as well?? Both ways your transcribing audio anyway...
I watched the YouTube demo with video transcription and editing feature, and the reviewer said it's very choppy, like it feels jumpy. Any plans to eliminate that?