HTML <table> elements are meant for tabular data, not for creating two-dimensional layouts. However, OpenScholar's only other non-code solution to have content in columns is to not write it in a Page but to write each piece in a Custom HTML widget and use the Layout to arrange them. Content in widgets is much harder to manage than content in Pages (or other post types).
The file type icons have an empty alt="" attribute but thinking about it, it is decorative and duplicative of the filename extension on the file link.
Curiously, attached image files are displayed rather than linked to; they do have the alt text associated with the file (there have been bugs where this has not been the case for certain Embed Media uses).
I roughly followed the instructions from a blog post at another school, How to Embed Google Drive Videos. I also went into the files Advanced settings and checked the box to disable the option to download the video. I've noticed videos in Drive even have an option to add caption tracks (this video contains no audio).