Test-NFT with video artwork not showing on Sepolia

Dear community,

I’ve uploaded a video file .mp4-format as my artwork for en ERC721 token. The video is exported from Apple Keynote as 1080 × 1080p30, 20.9 MB and optimized for web. On the edition modus in manifold the video runs. However, minting the token for testing purposes to Sepolia, the video is not showing up on Opensea (only thumbnail is shown) or Manifold gallery (no video or thumbnail is shown).

Does anybody have an idea?

Many thanks in advance

gm - Can you provide a link to the token? What is the codec/filetype of the video?

Hi Lyndo, thank you for your reply. Regarding various privacy concerns, I reply direkt to you. Hope this is ok. The content is intended to be private. I’ve added a screenshot with the details regarding the codec.

Here is the link to the token: Chroniken von Dipti - 40 Jahre Rückblick - pirate81 | Manifold

Hello Lyndo, the problem seems to be solved on mainnet. Nothing else was changed, however it seems that the problem occurs only on testate (Sepolia). thank you