How to add videos from pc to phone?

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http://forum.xda-developers.com – I'm a complete n00b. I'm just trying to figure out on how to send videos from pc to my phone for a while now. HTC sync manager allows only adding mp3 files to the library but not video files to send to the phone.. And copy-pasting directly on the storage card also isn't helping me. When I copy paste it to my storage card, i can't find that file on my phone again. it only can be seen through astro file manager. any other way to send files from pc to phone which can be seen on my phone after i disconnect it from pc? (HowTos)