Are TED presentations academically credible?
I think you are asking two slightly different questions at the same time:


“Are TED speakers and their ideas credible? (as in "likely to be correct")” I'd say yes, since TED's process for inviting speakers is at least as strict as that of many scientific publications. Most TED speakers are invited to speak at TED because they've become renowned scientists through their peer-reviewed publications.
“Are TED talks scientific (as in "usable to base your own science on")?” Here the answer is definitely "no", for the reasons you mentioned: they lack the information needed to be independently verifiable.


Note that this does not mean that their content is wrong or unscientific; it just means that the talks are incomplete from a scientific point of view, and thus not by themselves verifiable. But most TED presenters will previously have published the findings they present at TED in a regular peer-review scientific publication in a scientific format. 

The bottom line is: you should treat TED talks like you should treat Wikipedia: use it to quickly understand new and interesting concepts. But before you actually apply one of these concepts, verify them using scientific literature.