Clip shows
Every now and then when following a TV series, an awkward kind of episode comes along: a frame story is used—rather heavy-handedly—as an excuse to sum up recent story lines by showing clips from past episodes. After just having watched one too many of those, I googled and found out that this kind of episode has a name, it’s called a “clip show”. The rationale for clip shows is as an introduction for newcomers to a series and to save production costs. A
wikipedia article has more on this topic, including some history.