We appreciate you for taking the time to share such thorough feedback!
As Head of Product at SproutVideo, it is my goal to ensure we’re really listening to our customers and adding features that will benefit you and your business. I am happy to share that we are currently working on adding some of these features you mentioned.
We'll support animated poster frames and script uploading for closed captioning in the near future. In the meantime, if you have the ability to create GIFs, our Customer Success team can help you with a workaround to support animated poster frames.
Regarding audio files, we do support *.mp3 uploads, and you'll have all the same features available for video uploads, including the option to add a poster frame. If you'd like support for any other audio file type or have other feature requests related to sharing audio, please let us know.
Unfortunately, we do not currently have plans to build an Outlook integration, but we will add this request to our queue. However, we are working to improve our existing email embed options, so if you have any other feedback or specific requests, please contact us at support@sproutvideo.com and our Customer Success team will ensure your requests are added.