see far fewer sentinel and MODIS images on Land Viewer site than on sentinel playground or worldview
What Worldview does, it does very well, so for Modis stick with that. A possible advantage with these other portals could be co-registration. Over at Petermann, where 3-4 Sentinels per day can be taken because of the orbit, LandViewer shows 29 June as the latest. I don't know their update policy nor how rapidly the interface is diverging from Playground nor whether they respond to user feature requests.
There can be advantages to Playground, for example single-click to step back a year. I have not been to the usgs Landsat-8 interface for a while; they had been intending to add Sentinel-2AB.
For an easy time series, take whole-window screenshots (command - control - shift - 4 - space on Macs), then crop or resize to 700x700 pixels for animation layers. This may lose something relative to downloading original jp2 channels (which are cut to size) but it is a lot faster.
The CAA buoy area has far fewer visits and the June weather was so cloudy that it was difficult to resuscitate the 25 June scene (foggy 2nd frame, global contrast/brightness 3rd frame, CLAHE local contrast enhancement 4th frame. (The tools provided are not sufficient for this at either portal.) Bulk motion of ice over the course of a week is not apparent at the resolution shown.
The buoy gps may be much better for this. Note the WHOI 'movie" shows slightly varying azimuth (yaw), pitch and roll relative to the mast and camera axes. Those provide three elemental rotation matrices whose product could fix the horizon and tilt if entered in the perspective tool of gimp. WHOI could have done this on the fly but did not.