Embedded videos do not have any limits. If you are hosting a video on Helpjuice, there is a limit of 500 mb.
Helpjuice supports any image type or file type. Images and files can be uploaded to Helpjuice if they do not exceed 10mb in size.
Is there a limit to how many articles/categories I can have?
No - you can have unlimited amounts of categories, subcategories or articles.