CathInfo.com

Very interesting video.

This is in fact a problem with R&R.  If you say that an Ecuмenical Council can err, then a fortiori Pius IX could have erred in the Syllabus or in the Encyclicals in which he condemned Religious Liberty. 

If the Church did not have the foundation of Tradition and History, your argument would make sense.  Ecuмenical councils are only infallible because the pope speaks infallibly.  Either he uses 1) his extraordinary powers to define doctrine or 2) he teaches something which has been handed down from Tradition and explains its Apostolic origin.  The definition of the Assumption is an example of both.
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I'm not sure if the Syllabus is of the highest doctrinal weight, but it does have what V2 doesn't, which is a historical, consistent teaching against the errors he listed.  V2 doesn't have any historical precedent, so we know right off the bat that it's novelty.  Ergo, there's no way it can be infallible.
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Clearly the teaching of an Ecuмenical Council  t-rumps (I had to write it this way to avoid the dumb character substitution of t-r-u-m-p) a papal encyclical or the Syllabus, which he points out here was never signed by Pius IX but was just a collection or compendium of his various teachings, and so they retain the weight of the original teaching.

An ecuмenical council, or an encyclical or a syllabus or even an Apostolic Constitution are mere "docuмent vehicles" whereby a pope can accomplish his goals.  The dogma of the assumption was defined using an Apostolic Constitution, whereas Paul VI used this same type of docuмent for his new mass (no doctrine was involved).
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A good summary is this:  A council is a teaching for the whole church, usually for doctrinal issues and legal debates.  An encyclical is directed towards the clergy (primarily) and usually deals with social, religious or political issues.  An Apostolic constitution or Papal Bull typically deals with law or doctrine.  A Syllabus comes from the greek "to list" which is why this name was probably used (and is rarely used).
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All of the above "docuмents" (except an encyclical, which is only a few hundred years old) have been used to define dogma in the past.  Until V2, every ecuмenical council defined doctrine and fixed other problems, so that's why the have the reputation for being of high importance, and also the time involved. 
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But an encyclical is not necessarily less important than a papal bull or an Apostolic Constitution.  It just depends on the subject matter and authority used. 
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Now, this guy is wrong in characterizing Encyclicals as "lightweight" Magisterium but they're definitely at a lower level than an Ecuмenical Council.

On average, an encyclical is of a lower level than a council.  But, in theory, a pope could define a doctrine in one.  But that hasn't happened to date.

Assuming that Wojtyla was a legitimate pope, he clearly dogmatically defined that women could not be priests (his language being almost verbatim taking from Vatican I) ... and that was in an Encyclical if I recall.

Ok, I didn't know that was an encyclical.  In addition, he clearly stated that woman being priests is a "long held" (i.e. Tradition/Apostolic) rule.  Some theologians have said that this is an example of the OUM (ordinary and universal) infallibility but not Solemn infallibility.  In the OUM, the pope is referencing authority from Tradition (i.e. Universality of time).  In solemn infallibility (i.e. dogma of assumption) the pope can explain the roots of Tradition or simply invoke "apostolic authority", which is necessary for solemn pronouncements.  It could be argued that JPII did not explicitly invoke apostolic authority, but only indirectly referenced his papacy.  It was a weird use of language (or it could've been a false translation into english).