upload large video files 100 megs or over... is there a specific script for that?

There are bound to be many. Even the most simple upload script is capable of handling large files, as long as the configuration is all configured correctly to accommodate for such large files.

Also, if you're planning to stream such high quality videos back to individuals, ensure you have the pennies to pay the bandwidth costs. No so-called cheap host, such as Dreamhost, will allow you to stream those, no matter how much they claim to. They will make the speed a nightmare to force you away because it's not financially viable for them, even if many users are running well under their quota and resource limit.

By switching to a dedicated server, I highly doubt it'll ever become financially viable for yourself.

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