If you're still interested in my level streaming system, I will make the tutorial tonight.
Basically, I made a family for Loadable Sprites and a Loadable tilemap, a MapSection object which was a tiled background with the same size as the screen, and used local storage to load and save information.
The MapSection object is given a PID instance variable which stands for Positional based Identifier.
I assigned LoadableSprites and LoadableTilemaps the same variable, but the value is given from the MapSection that these objects are created on top of.
I then made a global variable called MapName, for the name of the map the player is playing or editing on.
You must know how to use the TokenAt function within Construct 2. I use this to save within the local storage MapName_Sprites_MapsectionX_MapSectionY and MapName_Tilemaps_MapsectionX_MapSectionY
I then would say, every tick, if player is not Overlapping a MapSection with the PID of round(PlayerOrCameraPosition/screensize)*screensize [this will check the current screensize grid section the players viewport is within]
Load from the LocalStorage the keys of the corresponding position and the positions up, down, left, right and diagonally from the player.
The keys themselves will hold the information for what Sprites and tiles to load when a MapSection is created. This is done by the player adding them.
The values themselves will simply be the JSON value of the families at that point in time.
After all that is done, just delete objects when the player is far enough away from them. Remember that they need to be saved with localstorage first though, or they will be completely gone.