The Upload Studio will be replaced by the new Xbox App for Social Sharing and edition...

Hi there!

Unfortunately you can only share gameplay clips on Xbox Live, OneDrive, or Twitter at this time directly from your Xbox. Uploading to YouTube from the Xbox is currently not available.

https://support.xbox.com/en-US/xbox-one/apps/upload-studio-sharing-clips

You should be able to edit 4K clips in upload studio granted you have an Xbox One X. The only difference between 4K clips and normal clips is that 4K clips are limited to 30 seconds but editing them should all be the same.

https://support.xbox.com/en-US/xbox-one/apps/upload-studio-edit-videos

Hey Jason!

Thanks for reaching out to us today. Game clips on Xbox are recorded, edited, and shared from the Game DVR feature associated to the Upload Studio app. The Upload Studio app is the only way to upload and share clips that you recorded from Xbox or Xbox on
Windows 10.

As of right now, I don't think there is a way to convert or transfer your recorded files that are captured using your internal graphics card. All clips are captured using the Game DVR feature and then edited and shared from Upload Studio.

Look over our
Game DVR and Upload Studio on Xbox One article online that goes over how to record and share clips on Xbox.

Hope this helps!

You can use the Upload Studio app on the Xbox to upload your captures to OneDrive. From OneDrive you are able to download your captures for sharing on your social media pages if you wish to do so.

Upload Studio lets you edit and share your recorded gameplay clips with the Xbox Live community.

support.xbox.com/.../upload-studio-sharing-clips

How are you going to share clips with a community your not subscribed to?

MS isn't forcing you to do anything.

Alternative buy the kit that will allow you to do it without live, (live is cheaper short term, or for getting used to it)

Regarding the clip trim issue, I would suggest freeing some space on your console by clearing the Mac address and saved locale games as they might be the cause of the issue. However, Currently Xbox Game Clips edit is only available on Windows 10 not on consoles.

If you haven't already, please check Manage your game clips | Xbox Support and Edit game clips in the Xbox Console Companion app on Windows 10 devices | Xbox Support articles for more information.