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 rear elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken line showing of various regions in the Figures, including the unshaded areas therein, is for illustrative purposes only and forms no part of the claimed design.