21. The system of claim 18 , wherein the physical computing device configured to determine that the level of correlation satisfies a threshold value is configured to determine that the correlation measure for the block to which a portion of the companion item of textual content belongs, satisfies the threshold value.
18. The system of claim 11 , wherein the physical computing device is further configured to determine the level of correlation between words in the portion of the companion item of textual content and words in the portion of the transcription by computing a correlation measure for a block of the companion item of textual content with respect to the transcription, the block comprising one or more portions of the companion item of textual content.