Hello Britt Rodriguez,
I just want to make sure I am understanding what you are asking. When you say attachments, do you mean embedding? Please see our documentation here: https://customercare.igloosoftware.com/support/knowledgebase/all_articles/articles/embedding_uploaded_files_into_the_wysiwyg_editor . You should be able to embed videos, images, and other files.
Currently you cannot attach files (https://customercare.igloosoftware.com/support/knowledgebase/all_articles/articles/attachments) within an HTML Content Widget. Only within blog articles, wiki articles, forum topics, calendar events, microblog posts, and comments.
Please let me know if you have any questions.