[BUGFIX] Use proper regexp for Vimeo URLs in online media helper

The change for issue #94357 introduced handling for `event/` URLs,
and accidentally modified handling for `video/` URLs as well. As a
result, the `video/` IDs were incorrectly resolved containing a
leading slash.

Resolves: #96509
Releases: main, 11.5, 10.4
Change-Id: I5623ff59dac44a699877e4e5a2e91707f72a407e
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/72969


Tested-by: Jigal van Hemert <jigal.van.hemert@typo3.org>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Jigal van Hemert <jigal.van.hemert@typo3.org>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>