In recent times, large video files could often be downloaded in the popular browsers by changing a URL path parameter like "r=1234567" to "r=0". I have downloaded many large videos that way.
DASH is used sometimes, but not on the majority of videos I encounter. Of course this can change over time. The point is that downloading large files today, e.g., from YouTube, Facebook, etc., cf. downloading large files in the 90s where speeds were slower and interruptions were more common, has been relatively fast and easy by comparison, even though these websites might be changing how they serve these files behind the scenes and software developers gravitate toward complexity.
Commercial "streaming", e.g., ESPN, etc., might be intentionally difficult to download and might involve "reversing" and "glueing" but that is not what I'm describing.
DASH is used sometimes, but not on the majority of videos I encounter. Of course this can change over time. The point is that downloading large files today, e.g., from YouTube, Facebook, etc., cf. downloading large files in the 90s where speeds were slower and interruptions were more common, has been relatively fast and easy by comparison, even though these websites might be changing how they serve these files behind the scenes and software developers gravitate toward complexity.
Commercial "streaming", e.g., ESPN, etc., might be intentionally difficult to download and might involve "reversing" and "glueing" but that is not what I'm describing.