There are several options, all of which are necessary, but it's very intimidating and kinda unwieldy -- especially for nontechnical users. A similar form is used to type in plain text.
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No suggestions about the form per se, all the options seem to be fine. A more spacious layout would possibly bring a bit clarity to the form.
You might want to conduct a usability test to the site/form with a handful of actual end users to see what are the most critical problems.
As a bonus, below are a few findings in general.
The user basically has three courses of actions, correct? Show three buttons that lead to separate forms or have all three options in the same form but all disabled by default.
Your current layout is initially confusing. Pasting a URL into a text field and typing text into a field are not uploading in the traditional sense, so labelling them as "Upload" is misleading.