500 Gigabytes is quite large. If people like media file types that are naturally large in size, you of course need a drive with a large capacity. However, media file types you listed, such as movies, music and photos are more categorical in nature. Video (or movies if you must prefer), sound (or music if you must prefer), and image (or a photo if you must prefer) files; these files have a multitude of varying file types associated with them. Each of these file types come with their own file extension. These differing extensions, and for example when viewing a video on a computer it could have a file extension of [.mpeg], or a file extension of [.mp4], or even a file extension of [.mov], these extensions, if the same video was converted into each of these formats, the sizes would vary. This principle of differing file sizes for varying file formats of media can be overlooked by common consumers. In order to optimize drive space, file size can be a considerable approach. It should be said that video quality when viewed on a computer machine depends on where the video came from; the external variable. This external variable would be the camera or camcorder, or whatever the device was that was used to capture the video. This device determines video quality. Once transferred to a computer, and I'll use Windows operating system as an example, as long as there is a codec for the conversion of the external devices captured video format, it would be best to optimize the video for storage space by selecting a computer media file type that takes up the least amount of space, all without loosing video quality from the source. Video files are no doubt right up at the top of all computer file types that take up the most space on any type of hard drive or storage medium. There are quite a few file types for any image file, too. It is best practice to optimize drive space by always knowing which file formats are best for differing media and documents. And with documents, I strongly believe plain old Text (.txt) files are the way to optimize drive space when writing up documents. In comparison of Text[.txt] files to a document processing program like Microsoft Word, Word documents when saved a substantially larger in file size when comparing to plain text documents. Substantially. Microsoft Word has its perks, no question. I do however believe plain text files or underrated and overlooked as a fast & low computer resource using text file process that takes up minimal hard drive space which means quick transfer times either offloading to an external hard drive, or uploading to an internet-based storage portal.
Personally, after optimization of media files, I would go with 512MB flash-drive for text files with [txt] extensions, 4GB for sound files with [mp3] extensions, and 100GB of space for video(s); just enough to house the imports long enough to burn to a DVD-R disc for portable viewing on any dvd player. I don't see any need whatsoever for terabytes of space, but this is me.
Any questions about this, you can quote me and I'll try to explain further.