We have sharepoint on-premise and online setup. We have a custom list and a site column of type Publishing HTML (Full HTML Content with formatting and contrarians) is added to this custom list. 
All the text based and HTML based content get successfully saved in the list. However, whenever video is inserted (from computer/ from sharepoint) it does play in the preview but once item is saved video code gets lost (iframe) (See edit snippet)
Same video works fine for multiple line of text column of type enhanced rich text editor .
we already have solution in production so cannot change column type at this stage. We tested this in both environment and cannot get it working.
Has anyone seen this issue?
NOTE: OOB Publishing HTML column created by sharepoint (e.g. page content) works fine and can play same videos. Just custom columns are having issues