Again it was very typical to add ornaments in Bach's day. If you listen to the solo Sonatas and Partitas, there are tons of stylistic differences and different ornaments people add onto what Bach wrote, a prime example being the Chaconne. Vibrato back in the baroque era was seen as yet another ornament, instead of something that you must do basically throughout, so it was used a lot more sparingly. Hilary Hahn's interpretation is definitely pretty romantic. The first movement of the double concerto is mind-blowingly fast and not in a good way. I don't think she realizes Vivace just meant vivacious or lively, this was before tempo names were given specific BPM ranges. Btw I don't think any off the string techniques had been invented by the baroque era either, unless you just mean a detache where the quick changes of bows lifted the bow off the string a bit. Will listen tonight.