I have been storing video / photos on some customer systems, and I specifically have one customer whose primary business model revolves around using Alfresco to manage high-resolution (large) photos and videos for various of its customers (publishing industry). In terms of "excessive" storage, long retrieval time etc it completely depends on how much / what storage you are using, and in some degree on how you are working with versions (each version of the content may be a separate file on storage). There are also techniques to use caching of content for potentially slow storage devices so users have faster access e.g. if they already accessed a piece of content before. Compression is not guaranteed to bring much depending on the format of the media file, and can even contribute to long retrieval time especially for large media files.
One of my projects (simple-content-stores) provides some content store utilities that might help work with such a use case, e.g. transparent compressing and deduplication of content to save on storage.
In general I personally do not see a problem using Alfresco for large media files provided your system setup is properly adapted to the use case.
