We have two different meanings of se retrouver here, and your understanding is correct for both:

• According to the TLF dictionary (see II.B-1. and II.B-2.), one of the meanings of se retrouver is too meet again (after having been separate) or too meet up (an organized way).

  Its use is very common on TV, live shows, or radio, but not only.

  So your example:

  Je vous retrouve pour une nouvelle vidéo !

  One could also say:

  On se retrouve ce soir, les amis ?
  (Shall we meet up tonight, friends?)

• I find myself (again) can perfectly be translated into je me retrouve (de nouveau): according to the same dictionary (see II.A-2.b this time), another meaning of se retrouver is to be facing an already known situation or to be suddenly facing a new situation.

  So your example:

  J’ai pris des questions de tous les tags, donc je me retrouve avec 30 questions.

  or

  Hier, dans le métro, je me suis retrouvé face à un fou qui m’a menacé avec un couteau !
  (Yesterday, in the tube, I found myself in front of a crazy guy who threatened me with a knife!)

  You can replace retrouver by trouver in this context. Both example above would work, regardless the fact this was a new situation. This is the meaning II.C.2. of trouver in the TLF which is to be, at a given point of time, in a particular state, position or situation.

  But note that se trouver and se retrouver cannot always be exchanged that way, this is limited to the context above:

  Je vous trouve sympathique, c’est un plaisir.
  (I find you sympathetic, that pleasant.)

  Is not the same as

  [Je vous ai quittée désagréable il y a un an.] Je vous retrouve sympathique, c’est un plaisir.
  ([I used to find you unpleasant before we left each other a year ago]. Now that we meet again I find you sympathetic, that’s pleasant)