The ornamental design for a mediaplayer, as shown and described.
FIG. 1 is a front isometric view of a media player showing our new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a left side elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is a rear elevational view thereof.
The broken lines, which define the bounds of the claimed design, and the broken line showing of the spaced border line around the display, the two buttons, and the remainder of the media player is for illustrative purposes only and forms no part of the claimed design.