Only 1 aspect can be imprinted on an item at a time. Aspects that you extract from a legendary item (that go to your inventory) are one time use only. You can not extract an aspect after imprinting it onto an item (no double dipping). Codex of power aspects (from dungeons) are unlimited use, but if the aspect has a numerical range to it, it will always have the lowest possible value (role).
If you want a standalone app and not a safari workaround, I recommend video lite. Works for twitch too.